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.