The free stuff isn't always as good, especially if you want something of a specific niche (fursuits, cosplay, etc). A lot of creators only upload cut-down vidros or "trailers" to free sites with a link to their OF.
At least in my case, I simply see it like the Patreon model. I like supporting some of my favorite artists, especially with something like an ongoing comic series I'll get previews of and vote on polls to influence. Onlyfans is the same if I particularly like some creator. It's great that we can directly support content creators of all kinds now.