Apple's proofread is essentially spell-check and punctuation until it isn't and even in a few-sentence-long para you'd see it has sneakily changed a lot and Apple being Apple you, the customer, obviously has no way to set it to "only fix spelling, punctuations and leave everything else including grammar as it is" and I've a feeling a lot of folks are at least using proofread or something on those lines. But then I really don't think browser's "spell check" ought to be kosher either if the content has to be the human's because those mistakes are also makes such text human and in some way unique. I don't think it's an easy line to draw but weird seeing just comments "targeted" here.