I posted about this phenomenon in the WAL thread. I will not reproduce the entire thing here, but in a nut shell here is what I believe is happening with many of these games.
The devs start out excited, motivated, working hard, they are cranking out content. They start making good $$$. Then they reach a point where either something just comes up, maybe they get sick, or they get a little burned out, whatever - and so they take a bit longer to do the same amount of work. Instead of 2-3 months perhaps it takes 4-5 to finish an update this time. But then they realize "huh, I still made about the same amount each month, even though I did less work this time."
This is where the problem starts. They start to realize, whether consciously or subconsciously, that thanks to Patreon, they can actually make more $ per hour by producing content slower, and there is really no great reward to producing it faster / reliably, because there are thousands of blind faithful fans who will continue to pay regardless. Plus it pays to stretch it out, because eventually they are gonna run out of ideas, and then their cash cow is dead and they better hope their next idea is as successful. And starting something new from scratch is a ton of work. Better to keep milking the cow slowly over more time.