At OnlyFans you're paying for a video feed, and computers are pretty good at producing convincing video feeds now.
I'm married now, and never used any parasocial platform OnlyFans or another, but trivializing the problem of young adult loneliness is either ignorant or condescending.
A large fraction of young males don't have anyone to "take out for a dinner", or at least have no idea how to initiate that. You may scoff at that, but I certainly wouldn't know how to do it, and money was not a problem. Paying for human connection, especially online, was tempting.
Which is probably fine if you're a successful man in his 40s who has more time than money and treats escorting as a shortcut. Not so fine if you're a man half his age who is struggling to find a partner.
Escort services are still a very niche interest in most of the world.
And they provide a simulacrum of human connection.
Then they can prominently state the chat is not with the actual creator, or they can go to jail for fraud. This "oh they say they're providing you X but you're actually paying for Y" argument is getting even more tiresome than the "fraud is so widespread why worry about it" one.