Scarblac wrote on 07/19/17 at 12:53:37:
Recently at my club, my FM opponent played 1.d4 Nf6 2.Bf4 g6 3.Nc3 Bg7 4.h4!?. I don't really believe in it, but that's the kind of thing that's out there nowadays...
Grischuk has played 3.Nc3 8 times now in my TWIC-based database, Karjakin 4 times, Aronian and Nakamura have played it too (all of those are probably mainly rapid and blitz games, but still).
Modern players have a HUGE repertoire of openings (especially for rapid and blitz). I looked at the Danzhou Supertournament games and don't remember a single London System. I think it's primarily used to avoid preparation (especially potentially long unintuitive computer lines like in the Sicilians or Grunfelds) and get a tiny but safe pull for White. It obviously has very different structures but it feels like the same goals as the Catalan in terms of trying to play for only 2 results. Anyway, Carlsen and Kramnik too more recently, have played pretty much anything which isn't terrible. Don't get me wrong, I think the London is a good opening but I don't see why it's so hyped and getting so much more popular.
People aren't even avoiding theory that much because they have to learn a new opening with its own theory (which is growing quickly)!
It's not the hardest to learn but that applies to BOTH sides and main line openings tend to have dozens of opportunities to play a good side line with an offbeat idea while generally putting more pressure on the opponent if they make a mistake. So why bother replacing one's whole repertoire with the London?
Personally, I find it fun trying different openings and just came off a 1. b3 stint so I might try it out. However, practically speaking, I think the London's advantages would only really apply if a player had not studied any openings previously. If you've developed a repertoire for a decade, then the London won't save you any time as opposed to just going some good side lines.
With that said, I've only played a dozen Londons as White in blitz games and the rest of my experience was facing it a few years ago (surprisingly, more in tournaments than online). I tended to go for hedgehog type positions and it was OK but it wasn't trivial to totally equalize. Once I started playing the Grunfeld though, I found the London extremely easy to deal with. g6 structures just seem to shut down a lot of the pressure from White's light squared bishop while allowing more powerful pawn breaks too.