Not everyone is a native English speaker. Not everyone reads and writes in the same way. Sometimes it is people's phones doing weird things.
But belittling someone because you, personally, have OCD and cannot just overlook the error is just as annoying to some as the errors are you to you. (Okay, and to me, but I take a deep breath and move on.)
There's no reason to be mean ... it is entirely possible that the person you are mocking is communicating in a non-native language or has other issues with spelling/cognitive function. I have a dear friend who is one of the smartest people I know, but he cannot spell to save his life. His brain just doesn't work that way.
So get your head out of your behind and stop being a supercilious (insert common nickname for male genitalia). If it really bothers you that much ... perhaps you should stop reading. Or just skip over the posts from those who commit these atrocious assaults onto your tender little eyeballs.