as a newbie I am wondering, can the developer create his own site and enable transactions ?
That's not really the problem he's running into. It's all about payment processors - credit cards, bank transfers, paypal transfers, pre-paid credit cards or charged debit cards. Some site software handles CCs just fine, but few of the others. And a lot of people seem to use Patreon (Paypal) for it's alternate ways of adding funds. Other processors may not want to cover adult (or illicit entertainment type) transactions.
From what I understand, Patreon is cracking down as they're going public in the near future (?), and want to appear like they don't have any illicit content they're backing.
And there's of course the problem of independent website security. If you don't have a dedicated security person constantly updating the site/code (or an entire team), you put yourself and your subscribers at risk.
Personally I go for the Venmo option myself, and got a Venmo card to cover online stuff. I keep my regular CCs for daily and professional use.
There isn't currently a really easy option to get around the draconian Paypal issue that's safe and offers all the same payment options. It'd be nice to see SubscribeStar step up, get some more approved payment processing options, and allow the same unfiltered content it's always had.