Well, chess.com spend quite a bit of dev time on gimmicks like their custom 4-player chess variant, that was followed by a torrent of 4 player chess content from their army of chess streamers. To convince someone to buy chess.com, they need to make themself look like the de facto standard site. They also need to invent new features because charging people just to play chess and solve puzzles online is sort of ridiculous when that's been available to people since the damn 90s.