A lot of the devs here do eventually release their game on Steam. So if you want to support the dev but don't want to pay the Patreon subscription you can just wait for it to be finished and then pay the 1 time cost to buy it on Steam.
I bougth a few on Steam even if I hate the platform. I prefer itch and GOG. I would also put gamejolt in this list, but sadly they changed their policy about a year ago and removed all adult games - also the ones I bought there prior to that change. They did allow to download these games for about a year after that change, now they are gone for good.
Just today I got two new ones from GOG. To buy on Steam a game must be very good and/or I must be very desperate.
This whole subscriber/patreon thing is not just about money (well, in the end it is, but not MY money). It's also about the whole system giving customers too much power over the creators. Since the project is not completely financed, the creators must keep people happy over a long time, implementing all crap which comes to their minds with all sorts of consequences instead of following their own vision. On the other hand since there is no pressure for them to stay on track and finish the project in time they can keep changing what they already made and change the plans they made, also delaying the production which as a consequence leads to people whining about being milked.
I can understand that this system allows absolute noobs to get into business and try but for advanced (don't want to say "professional") projects it just sucks.