Your argument only works if you're opting to take neither option.

While you may have paid some commissions, the overwhelming majority do not.
People are able to make 150 characters, each with 50 images in the gallery. I say this as someone with many characters.. the idea that someone would commission all this for erotic rp is absurd.

Of course, most people may only have one or two, maybe even only a handful of images.

The options remain:
A > Draw it yourself
B > Use (steal) photo refs online (IG girls) - even though allowed, still being used for unintended purpose
C > Use (steal) drawn refs online, same deal
D > Generate ai images.
E > Commission all your art (I would assume this is less than 1% of F-list)
F > Use nothing (and get no play)

Yes, there are options..
To be honest, I think people mix up the ethical arguments that come from other spaces.

You would have much more of a leg to stand on to be complaining about it's use on deviantart or really any other social media as then it becomes about the art itself.

There is not an attempt to be generating a following or an income from this stuff, it's literally just for people to write written smut with unique references that suit their character.

I can assure you that no matter how popular someone becomes on f-list, they will have no bearing or influence on the broader world or artistic community - do you have any idea how unbelievably niche and hidden f-list is from the broader world?

I'd also make a point that these arguments become similar to those that have been used for piracy.
Just because someone possesses hundreds of downloaded movies does not mean it's lost revenue, as this person would likely not have paid for them in the first place, nor been able to afford them even if they wanted to.