There's over 7,000 2dcg games on here. A decent chunk of them are pretty good games that never get the support the dev needs to keep moving forward.Well actually, the ones I see grind to a halt actually DO get the support to do it full time. I feel like that is part of the issue. They realise they are getting loads of money no matter how much work they put in. Patreon doesn't really incentivize actually working.
But you're right, with the way Patreon is set up it really doesn't incentivize putting work into a game. And it's heavily abused by not just game dev's, but artists and even authors too. But Patreon isn't going to make any change to its system, then they'd lose out on all that money.