1.d4 f5 reasoning

I don't know why, but I'm finding it hard to understand the rationale behind the f5 response to d4. Can someone explain it to me in a more concrete way? (I'm not good at thinking positionally).

Counterplay against the White king, or at least gain space on the kingside (eg, g7-g5, Qd8-e8-h5, similar to the King's Indian, and sometimes even a rook lift with Rf8-f6 similar to ideas in the Queen's Indian) and centre (d7-d6 followed by e7-e5, sometimes Nf6-Ne4).

When black is playing to win, they're often looking to unbalance the position in any way they can. It's sort of frustrating playing 1.d4 d5 2.c4 e6 3.Nc3 Nf6 etc when white gets to develop both knights to their natural squares, but black is forced to play Nf6 and Nbd7, plus playing c6 instead of c5, and having a hampered in queen's bishop. At least after 1.d4 f5 black can start out with an unbalanced position right from the outset.

Almost same reason why the sicilian 1.e4 c5 is played.Black controls the d4 square in this case and plays for a win from the onset.In chess, the more symmetric the game is, the higher the chances for a draw or black loss due to white's first move advantage.

So, mirror the sicilian... 1.d4 f5. controls the e4 square and progresses into a dynamic game. The only difference is the f-file is on the king side and black needs to be careful as it mostly leads to a sharp game.

Overall,its an interesting line worth playing.

to be fair.  e4 c5 good opening by both players.

d4 f5 good opening by one player, f5 is not losing but it is a step in the wrong direction.

It does make sure the game is unbalenced but really this is to the benefit mostly to white. Of course one inaccuracy means very little and this is what dutch players count on.

1 inaccuracy > being in opponents playground.

The better player will win the game in the dutch as is often the case.

The bird's view of the reasoning is as previously stated;
Although an engine would deem it "inaccurate", this means 0 sub 2000 rating, even higher up. 

Although we're talking about a position, the position in itself becomes tactical and sharp, thus giving an unofficial edge to the player more versed in such positions. Before I started playing it, 1 … f5 always confused me, as white. 
Now I love it. However, I do find it hard to actually force an attack. And ideally you would want the bishop from c8 to -> d7 -> e8 -> h5 to pin a knight on f3. 
This in combination with a rook lift from f8 -> f6 -> g6 is definitely unpleasant for white. However this requires a lot of losing tempos, but can lead to a bombing on the king side. 

Not at all good at its theory, but when 1 … f5 works it's a beautiful game. 

As one that has played the Dutch off and on (Classical and Stonewall, not Leningrad), what you said in your post is a common misconception by White players.  You say you cannot force an attack.  Many White players get this idea in their head that 1...f5 must be weak.  What many do not understand is that the Dutch tends to create more holes than say, the Queens Gambit Declined or Nimzo-Indian.  For example, the Stonewall has a glaring hole on e5.  The Leningrad has a glaring hole on e6, even if ...e5 and en passant is achieved, the e6 square is still glaringly weak.

The way to beat the Dutch (especially the Stonewall and Classical) is through taking advantage of positional weaknesses created from the opening.  Getting that dark-squared bishop trade in the Stonewall.  Achieving that good Knight vs bad light squared Bishop ending.  Paralyzing Black to guarding his own weaknesses like the e6-pawn.  Barring a gross blunder by Black, the Dutch is NOT beaten by King blasts.  White does not win games in the Stonewall Dutch in the same manner that Black wins games in the Kings Indian Mar Del Plata.

Temper your expectations and grind out the win against the Dutch.  Try too hard for the direct attack and it will almost surely backfire.  This is usually how Black gets his victories in the Dutch.

oh god here we go again. 

There is zero reason to think anyone has a misconception here. What he said was completely fair. 

You seem to consistently think you know what others do or don't understand. What many players "don't understand".... who are you to talk about this? Only someone rated several hundreds of rating points higher or who is a trainer or other experience dealing with people would have the ability to talk about "misconceptions" like this. Or if you wrote a book on that specific opening, then you could talk about it like that.  

Literally everyone knows the Dutch is a sharp opening. It can be positional for a while, the same can be said for the King's Indian Defence or many other sharp openings. You're gonna have a hard time trying to convince anyone an opening starting with moving the f-pawn is not sharp. 

Any beginner can confirm that white may win with a successful kingside attack against the dutch. Besides he is talking about black's chances against white, not white's chances. "in the same manner that black wins in the Mar del Plata" - wtf are you even talking about?! Like it's time to take a chill pill and reevaluate what you're doing and why, these are not accurate or useful posts.  

Well then, you just go ahead and try to blast the Dutch and get killed in 30 moves by whoever is playing Black.  I am not going to argue with you about your snotty attitude that you always have directed at me.  One more negative post by you directed at me and you are getting reported!

I guess he doesn't know what is the "Mar del Plata variation". Neither do I. 

The Mar del Plata is a highly critical variation of the king's indian defence. He's saying that you can't attack black here in the same manner that you would attack white being black in the Mar del Plata variation, where white doesn't even play f4 and is completely different as a result. He also assumes a kingside fianchetto, leaving out large alternatives like 2. Bg5. Furthermore the post he was quoting was talking about white attacking black, not black attacking white, it's as though he confused himself about the colours. 

Look!  I told you to stop knocking my posts.  That is all you do is find any reason to knock my posts with false information.

"FURTHERMORE THE POST HE WAS QUOTING WAS ABOUT WHITE ATTACKING BLACK, NOT BLACK ATTACKING WHITE"

DUH!!  And my comparison was comparing WHITE'S ATTACK AGAINST THE DUTCH TO BLACK'S ATTACK IN THE MAR DEL PLATA AND SAYING THAT WHITE WILL NEVER SUCCEED IF HE GOES FOR A HACK ATTACK APPROACH!  I NEVER SAID IT SPECIFICALLY INVOLVES THE F-PAWN LIKE YOU CLAIM.  I AM SPECIFICALLY SAYING THAT WHITE CANNOT GO FOR A SUCCESSFUL HACK JOB AGAINST THE DUTCH LIKE BLACK CAN IN THE KID MAR DEL PLATA!

QUIT SAYING GARBAGE ABOUT ME THAT IS NOT EVEN TRUE AND THEN SAYING THAT I AM CONFUSED WHEN I AM NOT!

AND ANOTHER CASE OF YOU PUTTING WORDS IN MY MOUTH - WHERE IN THAT POST DO I SAY ANYTHING ABOUT WHITE MUST FIANCHETTO?  HUH??????  I AM LISTENING!!!!

Because for it to bear even the slightest resemblance to a reversed Mar Del Plata and a kingside attack to be even partially ruled out it would have to have a kingside fianchetto. 

Blah Blah Blah- You have made one too many assumptions and one too many attacks on me for things I did not even say.

YOU ARE REPORTED!