Oh my sweet summer child, this is 100% a pirate site. It just so happens that some developers realize that all publicity is good publicity, so it's better to cooperate (and thus retain some influence and control) than to fight it and accomplish nothing.
If Selebus did not post here this thread would continue to exist, and the main difference would be that the "patrons only" build would likely get posted a day or so after the release instead of waiting for the public release. But, since Selebus is involved in F95, he owns the thread and thus can protect the exclusivity he promised his paying patrons. This is acceptable to the (largely piratical) community, because having him here offers other value-- we know he reads our feedback, he answers questions, etc.
In addition to some modest level of control, the developer also benefits because (a) the feedback here is a bit more broad-based than he will get on Discord or Patreon, where nearly 100% of the feedback is written by serious fans who will only have nice things to say (otherwise they wouldn't be there), and (b) it gets more eyeballs onto the game. (I follow many games on SS and Patreon, and in most of the cases I found them here first, played the pirated version, and decided I liked it enough to support the creator. I'm sure others do this as well.)