I know the pattern that you're referring to is evidenced heavily in some of the bigger titles on patreon, but I refuse to believe that Tinkerer is at all influenced by the rampant greed patreon permits. As games get larger, it takes a lot more time and care to make sure that critical bugs don't pop up all over the place. In this game's case especially, Tinkerer is jumping around updating various strands in a web of plot threads so his patrons feel that they have a say in what gets updated first through voting. If a game dev had a set schedule and plan from start to finish, and repeatedly bucked on their deadlines, I would agree wholeheartedly that there's probably more to blame. Tinkerer works alone with the exception of a few people who volunteer to help him bug test. He went out of his way to alleviate the censorship that Patreon forced upon his game, something most devs don't have the guts to do given the risk.
He has a habit of promising more than he can deliver, and I know that can be frustrating for people who thoroughly enjoy his work. But try not to bash on him too hard. He's a good guy, and I'm almost positive that he reads this thread from time to time. I'd like to think we wouldn't want to discourage him and slow the updates down further.
TLDR: The pattern you're noticing could be caused by a natural difficulty in programming as a game gets larger/closer to finishing (something that also tends to draw more attention). I agree that some patreons milk their patrons, but Tinkerer isn't one of them.