Up until Dec 15th last year SS banned nothing, not even lewd 10yo lolis riding their daddies in high end Daz (and prob not realsitic AI either, though few even try to for legal reasons). While those are no longer allowed those devs now have face projects no one cares about under different dev names to subsidize what fans are actually subbing to and promoted on loli-friendly sites seemingly for free if you are not subbed with access to their private Discord. (ie The face project may get 1 small update a year and be boring and vanilla as possible with only missionary positions and only after the MC marries his LI to keep up appearances while the actual one is every 3 months or so). As far as incest Steam allows it (just no lolis or anything even remotely suggesting they are <18), SS allows it (and always has), and so just about every other platform allows it. The key reason is they are on a different payment network than Patreon (mainly not Paypal) so they have more lenient masters to bow to. Real porn sites tend to disallow it but even some of those simply choose to make less money and only deal with the non-prude PP's and also have  real/non-step incest (and scat,bestiality, etc like Luxure.tv, 9vids, Motherless, Heavy-R, etc).