Why YSK?
The first person who typed “should of” probably heard of it in real life that was meant to be “should’ve”, they typed “should of” online and readers thought that it’s grammatically correct to say “should of” which is in fact wrong and it became widespread throughout the years on Reddit.
I hope something could start to change.
Isn’t “have” either an auxiliary verb or verb and “of” a preposition?
Are these acceptable? If yes, why? If not, why not?
I of heard that story before.
Diane of already gone.
John ofn’t phoned, of he?
I ofn’t visited London before.
Of you seen Roz?
Of she been invited?
They still ofn’t of any news when I spoke to them yesterday.
I don’t know man, Oxford Dictionary (click Grammar Point to expand) says that https://www.oxfordlearnersdictionaries.com/definition/english/have_2
Tells us what’s popular; sometimes also what happens to be correct.