It depends on your view of language. Is language a set of clear conventions that describe what skilled writers and speakers are supposed to do? Or, is language simply what people write and speak?
We could treat those two views as a line between the 'conventions and rules' approach and the 'It is what it is' approach.
We might not agree if we chose our positions on the line. I'm well over the centre line in the descriptive, 'It is what it is' territory. That leaves some room for rules, but only where they help to make our writing easier to read, absorb and remember.
Can we agree that it makes sense to go along with convention at least to some degree? The plural 'are' goes with 'we' and the singlular 'is' goes with 'she'. 'I are' seems jarring to most ears and encourages people to think we missed some essential years at school.
The problems come with the myths.
I'm a defiant splitter of infinitives. I see no problem with 'to boldly go where no man has gone before (Star Trek)'. Apparently we're not supposed to split infinitives because you can't do it in Latin. The logic of that argument is a mystery to me.