What's with the backward knight moves ?

Since some months I see this pattern more and more.
Castle short as soon as possible, and then throw back the knight.
Popular at lower rated players, but I see it appear more often in GM games as well. What is going on ? What about the focus on the center and centralizing pieces ? Which chess video streamers are pushing this idea ? :)

Can you link some GM games with the maneuver, @achja ?

The only time I've seen this done was to put pressure on a pinned f6 knight.

looks dubious at first glance

@Rrhyddhad #2
If I remember correctly I saw it in the last few months in a game by GM Anand in Ruy Lopez or Italian game.
Actually, I remember now that years ago I saw a game by GM Portisch, playing Benoni as black (!), going for h7h5 and Nf6-h7. I was amazed to see that, never saw that idea in a Benoni game before.
Also, I remember now as well, that in the King's Indian Attack (e.g. in games by Bobby Fischer), white plays h2h4 and Nh2-g4.

In the King's Indian attack it is standard, but there the centre is closed with the white pawn on e5.
I have seen it in the Giuoco Pianissimo Italian by Carlsen: h3, Nh2 and then f4. There too the centre is fixed.
In this game the centre is fluid, and that enables black advantage.
Besides the doubled pawns are an asset for black with the open g-file and not a liability as many weaker players seem to believe.

It's not always a bad move to bring a knight backwards there are a great number of reasons it can be a good move.

-It unleashes some other longer range piece
-The king needs it for some desperate defensive purpose
-It must retreat to avoid being hung
-It is part of a maneuver to get it to a good square
-It traps some far advanced enemy piece from getting out
-Something has changed in the pawn structure, and it must go back to go another way

On the other hand from a pragmatic sense more often than not it is a generally a bad idea to retreat a knight.

Ch2 - g4 it is a fairly common variant in Spanish

Dominguez (2719) - Caruana (2652). 2^ partita di spareggio rapid. 1.e4 e5 2.Cf3 Cc6 3.Ab5 a6 4.Aa4 Cf6 5.0–0 b5. 6.Ab3 Ac5 7.a4 Tb8 8.c3 d6 9.axb5 axb5 10.d3 h6. 11.Te1 0–0 12.h3 Ab6 13.Cbd2 Ce7 14.Cf1 Cg6. 15.Cg3 Te8 16.Ch2 d5 17.Cg4 Cxg4 18.hxg4 Dh4.

Today again an opponent who focused on backward knight moves, and guess what ? Turned out that I blundered right away. My opponent however responded auto-pilot with knight-backward-goes-forward, but g2g4! and then g4g5! would have given white better to possibly winning advantage.

Since it is no longer the opening, I think it's to re-position the knight. Knight was doing well on the original square though.

Because knights are clumsy pieces, often blocked from forward movement by enemy pawns and friendly pawns, the only way to -re-position it is to move it back.

Doesn't seem to be the best move though, white resigned in this game...