Chess has been played for ages with no dlc. Competition against another person is engaging on its own. And chess is a good deep game on its own.
Combine competition with a good game and you get a successful infinite live service game in theory.
Only one or the other and you get a flash in the pan.
Theres plenty of high quality content on youtube though. You gotta wade through wall to wall youtube cringe to find it, but once you got a list of good subs, that problem disappears. The idea that youtube is solely garbage low effort content is so outdated