I think I may have triggered this question from you, Habib, because it came after I used the phrase in an answer.
I do in fact have a rule of thumb answer. It’s based on Laura Hale’s observation of how many followers and views typically get you Top Writer.
(If only it were that transparent, of course.)
I may misremember, but I think she said it was at least 300, and my own rule of thumb has been 500.
Yes, yes, I have 650.