@Kinkys-0 I suspect that in addition to things like DMCA...
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Sorry, I was waiting for a troll to interrupt me. Anyway, in addition to things like DMCA I would say that any given video's availability is directly linked to its popularity. The more people that like it the more likely it is to be widely shared.
The perceived value for money on the source site is probably also a factor. If a site seems overpriced or has limited offerings then it's less likely to get subscribers who can then share. That will certainly slow down the dissemination of new material from that source.
It's interesting to see some of the studios you've listed; Femboyish, CumDumpSluts, BoyForSale, Gaycest, FunSizeBoys, Scoutboys, TwinkTop....... I've seen loads of stuff from all of these spread across the 3 "main" gay torrent sites, so I can't help but wonder if you're just not noticing them.
Take Femboyish as an example. It's a relatively new label/brand (only about 18 months old now I think) and I've found reference to around 37 videos produced under that moniker, of which I've grabbed 27 without much effort at all.
Another is CumDumpSluts. I've got 17 of their 34 productions to date, again just from grabbing them when I see them rather than actively hunting them down.
I think that if you see yourself as a compulsive collector who must have everything from a studio then you're going to need to open your wallet and pay for access, because the likelihood of finding a truly complete set of files from any of them via torrents is unlikely.
It took me less than 15 seconds to find this simply by searching for "fiance"