PayPal get a sniff of your business transactions is related to adult/porn entertainment quite sure it would get cancelled fast. It still fly on Patreon because Patreon is so much more than just people creating games for adults. If that had been all it was, they would lost Paypal long time ago.
Also it's not about there is "other" payment processors out there. It's about what people feel secure with and what they feel at ease with. PayPal is that thing. Not everyone feel like throw their cc details around on the internet willy nilly.
If things been as easy as you portray it all these creators would done so right?
Patreon is EASY. That is it. It's not better. It's not a way to avoid Paypal's ToS. It's just a simple, one-stop-shop for the amateur dev who doesn't want to deal with those issues like maintaining a website or monitoring the finances.
Most of these Devs are just average people, like you or me. They have an interest in these games, they have access now to amazing 3D modeling tools like Daz3D and so they took a chance and made some games. I love how much this industry has exploded in the last 6 or 7 years! Heck, I used to spend hours trying to download Japanese games from websites that I couldn't read, then fucking with the files and Windows to make them work on my computer. Those days are gone... now there's this whole 3DCG VN industry in the western world where anyone with a computer can self-publish. And occasionally, some real talent comes out.
Don't drink the Kool-Aid and think that losing Paypal is that big of a deal. Paypal has had their share of hacks and breaches. I know... I've been a member since Ebay bought them out in 2002. The porn industry has helped create a whole industry of secure online payment processors. Porn's like that... lol. Paypal is just one of the many recent giants that is trying to go more "clean" . Just look at Mega... created by one of the biggest degenerates in the world and now they are trying to back away from their own roots and put this white knight image to the world.
IMO, what it boils down to is that these devs start out with noble intentions, making the games/VN's they have a kink for (and this dev still refers to all the incest on his website) but they get hooked by the easy cash of Patrons and they don't want to lose that. That's fine really... it's their business after all. I doubt they enjoy the bastardized versions of their creations though. And they also miss out on the opportunity to make more money doing what they originally wanted to do. It just takes more effort to make that happen.
As for what customers feel comfortable with... In my experience, anyone even remotely touching this world (porn-porn games-etc) are well aware of the risks and many of them use seperate CC's or Debit cards to limit their risks. What they like is to do things easy and safely. Oh, and BTW... Paypal is possibly one of the worst services to use for any "Shady" puchases. They keep logs forever. I can go on mine and download transaction details for things I bought 15 years ago! At least with pre-paid CC's, you can limit your exposure. Just saying. You don't want your ex-wife throwing out details of the creepy porn games you paid for at your custody hearing, then don't use a service like Paypal to pay for them.