King's Gambit Accepted: why not h3 to prevent g4?

In many KGA lines, it seems that white often plays h4 in response to black's g5, but then ...g4 kicks the f3 knight around.  Why don't I ever see h3 as an attempt to keep black's pawn out of g4?  Why is h4 preferable to h3?

DISCLAIMER:

I do not play KP openings.  This is simply what i see.  I am in no way saying my analysis is correct, accurate, or even on the same planet.

Hello.  Yes, this is the position I was referring to.  Thanks for the helpful information and explanation. I see the weaknesses on the dark squares.  It seems that White's knight gets kicked away easily and often gets sacrificed on f7.  Maybe that's the nature of the opening, though.

In the scenario above, couldn't white eventually castle queenside and then develop a kingside attack?  Especially if he can preserve his knight?  Thanks

Your second scenario is very interesting.  Your perspective is better than mine even if you don't play this line.  I'm just learning about it!  I don't play KP openings either, but I'm looking for something new to try.  Thanks for your insights.

Glad to help.  Hopefully someone better comes along and gives you a better explanation.

The problem with 4. h3 per your line is that the move is too slow. It gives Black more time to do what he wants to do. Also it makes the dark squares around your king a little weaker.

Right, it's too passive (for such a messy double-edged position), otherwise it would be ok to prevent g4. 

you don t need to stop g4 

white has sac  knight but have very stong attack

4. h3 Be7 and now it's really dangerous for white to castle kingside - which is kind of an important thing in the King's Gambit, because you want a rook on that semi-open f-file.  As noted by others above, gambits only work well if the player giving up the pawn plays aggressively, and h3 is not just passive, it is positionally weak on a side where you've already conceded a pawn majority to black by virtue of the gambit.

Just to piggyback on what others have said, why do people play the King's Gambit?  It's to offer a pawn for quick development and get the attack; every tempo matters.  Playing h3 would almost be the exact opposite: it's our third pawn move in the opening, after only four moves!  

[Edit: Of course, the mainline 4.h4 is also a pawn move, but it forces Black to do something.  It's an active pawn move.  4.h3 does not force Black to do anything; he can respond any way he wants.  That's the difference.] 

Openings have different 'flavours', if you will, and your play needs to match that flavour.  A gambit in an open position demands a different approach than a blocked, closed position.  If your play doesn't acknowledge this, you are likely to be in difficulties very quickly.

Since we're on the topic, what if White plays 4. h4 and Black responds with 4. ... gxh4?

I've played the King's Gambit a ton of times and today for the first time someone did that. I was so surprised, I didn't know what to do.

What is the best reply for White?

Couldn't you take with the knight, since it is protected by the rook?  Queen can't take and h file for black is closed...?

To-heal: thanks for the link.  I am familiar wit the sacrifice on f3.  Another line is a knight sacrifice on f7.  Have you played this line at all?  Seems like a wild beginning.

I am familiar with this video and this website: pretty helpful introductory stuff, which is basically my level!  Thanks again.