f5 is worse, f6 is terrible, lol white doesn't have to play like that either he can play better
Is f6 really that bad?

Yes it is TERRIBLE, and the only reason they COULD have been successful was because their opponents didn't know anything

So I did quick analysis with the latest Leela net (J13B.2-220) , and she will play like this. Both variation lead to serious problems within 10 moves of opening!

After move 5. h4. I let her play the best defense for black, and she will play like this which can lead to survival in opening but very crampy!

DEAD!!
well, of course playing f6 and g6 is stupid. Playing f6, you'd want to push e5 and pray pretty much
Well, I am also surprised how Leela found very sharp lines!
I met those opening several times and could not find a sharp solution. (bullet games)
4. Bc4 and 5. h4 are seriouly strong moves.
Normally people (also Stockfish play 4. Nf3) and 5. O-O and black can survie in the opening.

DEAD!!
well, of course playing f6 and g6 is stupid. Playing f6, you'd want to push e5 and pray pretty much
Well, I am also surprised how Leela found very sharp lines!
I met those opening several times and could not find a sharp solution. (bullet games)
4. Bc4 and 5. h4 are seriouly strong moves.
Normally people (also Stockfish play 4. Nf3) and 5. O-O and black can survie in the opening.
But if you really want a kings Indian against e4, there is something called the pirc....
I dont need Pirc, I already thoroughly prepared Caro Kan for 1..e4.
In bullet and blitz, it is very easy to set up a good opening reperorite for yourself. It is often hard to punish opponent crappy opening that you havent seen before! (In this opening , now I analysed and I know how to punish, but there can be another 100 crappy opening from opponents) . It takes time to analyse as well and many people dont want to spend time doing those stuffs.

Luck !! Author of book Barnes Defence for advanced players, gra-grandson of Thomas Wilson Barnes (https://en.wikipedia.org/wiki/Thomas_Wilson_Barnes) allow to public whole analysis of Barnes Defence for black player. There is 365 variants: https://www.dropbox.com/s/i5w3bp17xy9kd6z/barnes2.pgn?dl=0
Some variants where black is equal or better
All white's lines are really weak compared to Leela's lines. I wonder how many moves your 2600 human will survive against Leela. If you want to see Leela' Lines, I mentioned in previous page.

But I play chess not against Leela but against human. And human will be want punish weak mode 1....f6. And it is chance for a black player. At first 1...f6 is weak but not "so weak". At second, after 1...f6 there are very uncommon pawn structure and is not so easy to find correct plans.
Lol, I just look at wiki of the guy , he was a player from 19 century Lol.The moves you showed are like skill of 2000-2200 at most at today standard of play.
It doesnt matter whether you play vs 1000, 2000, or 3500 machine, principles of chess is the same.
Look at the examples of moves from white player, they are utterly aimless pawn moves or moves without synergy or plan.

oh i sparked a huge debate
Anyways, I playtested it against a CM and a NM, both 2200 blitz. I scored about 37% both matches,so it isn't unplayable.
I am a King's Indian player. But I obviously can't play it against e4...Or can I?
It looks dubious, but It transposes to a line used against the Averbach KID. I am wondering if this may be playable in blitz to eat time, confuse opponents, or set a trap and still get a decent position. (I would never play this OTB)