It's true, there's no online infrastructure for crumble. The irony is that crumble is one of the simplest games to make out of cardboard. At one point I figured out that you need 108 starting-sized squares. Then as you play, you cut those down into smaller pieces as needed. After a few games, you don't need to do so much cutting anymore. You've probably seen the quora post since you mentioned it, but anyway it's here:
https://www.quora.com/How-do-you-make-a-Crumble-set/answer/Zachary-Brown-25
Eventually crumble will make its way into all the online game-playing communities. But for now, since you're actually interested enough to make your way here, maybe try making a set for yourself and introduce your friends to it. I think that kind of local activity is really how crumble will gain popularity for the near future. It's like tic-tac-toe -- nobody buys a set of tic-tac-toe or goes online for it, they just play. And 108 squares are not such a big requirement. If you want starting pieces that are 32mm to a side, you could cut them all out of a single sheet of cardboard that's slightly over 35cm (14 inches).
Actually I think the game board itself is the harder thing to make. It needs a ridge around the edge of the playing area, and the enclosed region needs to be just the right size to hold the pieces, while allowing enough leeway to let people pick pieces up and drop them in without difficulty.
Be well,
Zack