But this is a matter of marketing, and good marketing can do quite a bit (its generaly the most powerful tool to get more sales).
Just imagine that the support is there, and now someone on onlyfans decides to use a script themselve, while allowing others to sync their handy to that. Instead of giving a single person control, it can just accept any script. The video might not even matter here.
Proper marketing can get these things started, even if initialy the start is slow. And marketers on that will obviously be aware of the anal part with it (as after all its a selling point). Even if onlyfans content creators might not give them enough sales, thats doesnt even have to be their primary target, the target is making the product known (and therefor creates extra sales). And this can be a good way to achieve that.
Add to that the potential of marketing to women to be able to now also enjoy PH videos. They might initialy not realy have cared, but women are still often curious about these things. But this obviously only works if the support is done well. Its still a toy that avoids a women to have to do things manualy (they are just as lazy as men here).
And sex is often already a matter of stimulating your brain, and immersion with a video is a way to achieve that. The main downside here is that if these things becomes too popular, men will have less chance of finding a women (although, maybe those women will also become more interactive with communities online)
And note, dildo devices are often already very cheap compared to stroking devices. Yes, there are big fucking machines that cost over $1000. But some cheap alternatives go under $100, and these are often the ones they start with because why spend $1000 if you arent even sure you will like it? Not just that, often the $100 ones use mechanisms that are a lot more suitable for funscripts anyway (its the $1000 ones that often cant, except they provide signficantly more powerful thrusts in return)
Altering a device might cost a bit, but if a good thusting toy already costs $250, adding $10 to that for funscript support (and with it, general interactive support) can give a nice return on the investment. But maybe the support on its own already generate 5% more sales.
But again, its down to a marketing department to realy get the value out of it.