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.
Well that’s what’s happening here isn’t it. It’s a word that is potentially gaining an additional use as a result of reanalysis. Whether it sticks around long term remains to be seen, but language is defined by usage and it’s foolish to pretend there’s such a thing as objectively correct. Already the use of the verb ‘to have’ to form the perfect in this case is quite different from it’s other meanings related to ‘to possess’. And that’s not even getting into you describing nonstandard usage as the result of ‘mush-mouthed laziness’ which is a whole nother can of worms.