I'm reading a copy of A.S. Byatt's Still life from the library which has been liberally annotated in blue biro with grammatical 'corrections'. Every incidence of the word 'whilst' has been changed to 'while', which is sort of fair enough. Every Oxford comma has been carefully scribbled out. But this reader isn't familiar with the subjunctive, so 'Tony insisted that Frederica come to hear Amis speak' gets modified to 'Tony insisted that Frederica should come'. 'As though this were possible' has been changed to 'as though this was possible'.
Further into the book the self-appointed sub-editor has been carried away with his or her own rightness. 'Last but two' becomes 'antepenultimate'. 'Nature ramble' becomes 'nature walk'. 'I think he might give up on me too' is weirdly changed to 'I think he might give me up too' which is quite a considerable change in meaning, I think. It's very disconcerting reading a book in which the author's language has been so assertively changed by a completely random person.