I know. Just like misuse of the word “To” instead of saying “Too” or “Your” instead of “You’re”. It’s grating. Many of these posters are otherwise quite literate and learned. My guess is at some point about 25 years ago, the American School System collectively decided to stop correcting people about such spelling errors because computer systems such as Spell Check would soundlessly fix it for them. So the lessons of correction have never been learned to this day.
In my case I have simply had enough of correcting the damn spell checker.