I've been reading a lot of fan fiction-turned published fiction recently (e.g., The Path of Ascension, but also a lot of crappier books that I get 10% through and put down), and there is an emergent hole in the new books on the (self-published, Kindle) market; despite having no editor, they generally have pretty good spelling, complex narratives, and not especially bad writing styles; they certainly do more writing than I ever managed. But they don't know their vocabulary. A 'overstuffed bag' becomes a 'teeming bag', 'nuclear deterrence' becomes 'nuclear dissuasion', 'unscathed' inexplicably becomes 'unchecked'. Some cases are maybe spelling errors, like when 'hotels' becomes 'hostels', or honestly not caring, as when failing to notice that a rapier is not a double-handed war-sword.
My theory is that spellcheckers and/or Grammarly give people the feeling of having proofread without having actually proofread. My other theory is that a lot of editing on the fan fiction sites where these tales are often born comes from people who are happy to point out something simple like a misspelling, but have learned that meanings are simply not worth it. My other-other theory is that most people don't care about the precision of words the way I do.
Regardless, with the exception of Mother of Learning, which glorifies in being written in the style of a poor translation, this sort of nonsense, if done repeatedly, is a major strike against a book, approximately one third of enough to make me put the book down.
Anyway, insofar as I have a point, keep your proofreaders close and your pedants closer, as they will be the ones to red-pen you out loud, while your readers will do so only in silence.