Not wanting to be purposefully controversial, but language is a tool for communication and as long as it’s understood by the target audience, then I’d say it was used effectively.
The English language doesn’t have a governing body (unlike say French and Spanish) and so whatever we agree on is correct usage. “Grammatically incorrect” has long been a dog-whistle signifier for elitism (you don’t have the expensive education to know what’s correct) and racism (the local dialect that you speak isn’t our ‘prestige’ version, therefore you are inferior) and I don’t really like to see it. Even when those aren’t your intentions when correcting people, it still rankles with me.
Not that I’d write ‘should of’ on my CV or anything, but it doesn’t offend me any on an internet forum.