I'm not knocking down anyone's decision for how to earn money or spend their time, but the porn industry in general (corporate or indie) is notorious for exploitative attitudes and behavior, whether it's Pornhub exploiting unverifiable nature of some videos and favoring turning a blind eye to the whole thing until tension mounted, or a someone being in a relationship with someone else and doing videos together because god knows how much fucked up shit they've been through by the time they became 18.
I'm not in favor of big corporations, but in this case, the rules made by Mastercard seem sensible to me, and I'm not surprised that the Pornhub/Onlyfans are gonna position themselves as "being forced by the big companies to abandon the creators they support".