I don’t know about you, but while I have an excellent command of formal grammar, having once had a nerdish obsession with learning all the technical terms, I deliberately missapply grammar sometimes for effect.
I’ll sometimes write in the vernacular I grew up with or use colloquial expressions. I prefer to write in active voice most of the time, but I use passive voice when it seems more appropriate or useful.
I avoid adverbs in creative writing, except when I don’t. Adverbs are sometimes very useful in opposition. For example, He ran quickly might be better replaced with He sprinted or simply left as He ran. But He ran languidly is a good example of an adverb performing an unexpected and useful function.
I learned about adverbs in opposition from an alumna of the Iowa Writers Workshop, so it’s not like this is just my own crazy idea.
But this isn’t something grammar checking packages are sophisticated enough to deal with. And neither is intentionally using non-standard grammar for effect.
As an editor for a Medium publication myself, I appreciate it when writers make sure basic grammar is in place, but I have to be careful not to stifle their authentic voice.
I could never take that care if I relied on software instead of my own eye and judgment.