The Critic article doesn't debunk the 4% statistic - it claims it is questionable and gives reasons why it thinks so.
'None of this is to encourage complacency. Clearly, many British women are using OnlyFans, seduced by misleading promises of easy money or in desperate need of cash. But the “4 per cent” statistic seems highly dubious and should not be accepted as fact."'
I also think you have mischaracterised her article. She writes about the dangers of unchecked sexual liberation - to women in particular. She's sympathetic to the women on there, clear that the women are often damaged or trapped or naive. And says OF is an exploitative dynamic on which most women earn a pittance.
She describes the work as "gruelling, disgusting, painful and dangerous," and highlights extreme escalation (e.g., Bonnie Blue's stunts, Lily Phillips' 101-men challenge ending in tears) as part of a "cascade of depravity" where creators compete for more attention. I don"t think she is sexist as much as she is primarily concerned with the impact upon women.
For some reason your link to the article didn't work for me - but hopefully this one will if anyone wants to read it.
spectator.com/article/why-onlyfans-has-young-british-women-in-its-grip/