No, the author's right. I can't believe how degraded written English has become over the last decade or so. This website is a prime example. It's actually becoming hard to find two consecutive posts with no spelling, grammatical, or punctuation errors in them.
The language isn't changing, but the quality of instruction and standards are.
Don't forget the utter absence of any warranted paragraphs (sometimes perhaps because they do not know any html). Yet as this forum is rather informal, I often do not proof read as I should before I post, and usually use lower case "i" for myself to save time. I also think grammar rules should have some flexibility.
You are right, of course. Maybe those of us who can't help picking up these glaring errors should adopt a whole different mindset. There's a good chance that said posters may be more caring, more giving, more productive, etc. than the grammar police.
Anyway, I don't mean to preach---it also rubs me the wrong way!