BGG is heavily about[1] the
board game night experience. Family, gamer group, newbies with a seasoned board gamer showing them some new games, that kind of thing.
Two-player games tend to suffer in the rankings to begin with, for that reason, though some do OK. Two player games with long or highly variable play times tend to suffer even more. Two player games that a brand new player is unlikely to enjoy playing against someone with even moderate skill is an even bigger handicap.
There’s also, undeniably, some novelty factor, especially near the top of the lists—which is part of why crokinole’s ranking is so remarkable.
Approximately nobody is breaking out chess or go at a board game night, even as a sidebar game for two players while they wait for others to finish a larger game. Maybe speed chess, I suppose. But in general those are less “we’re having a game night” and more “we’re having a chess/go/backgammon night” sort of games. Like, if someone’s not into chess and you suggest a chess match to kill some time waiting for the rest of the group to show up, they’re probably going to be less-happy than if you pulled out any of dozens of lightweight, quick 2-player games with fairly good BGG ratings. By that metric of game night suitability, chess and go et c. aren’t top-100 material. They’re less board-gamer games and more chess-person or go-person or whatever games.
[1] By this I mean the preferences and interests of the active parts of the community tend to run this way. You see lots of midweight attractive-looking newb-friendly (and also well-designed!) games good for multi-game gatherings, and big baroque “we’re getting together for six hours to play one single match of this game” games near the tops of lists, as a result, as those are the two kinds of game-playing gathering that are the ideal form of board gaming for the crowd there. It’s not a place with an unusual density of chess tournament fans, you know?