Print-and-play board games are just not very popular as a whole. Out of the 61K physical games on itch, only 2.6K (4%) are tagged "Board Game": https://itch.io/physical-games/tag-board-game
Just looking at the top games on the list, a portion of them are in fact TTRPGs or zines about board games (and not actual board games themselves), so the actual number is even lower.
I am interested in seeing more board games though. :)