Using incorrect grammar makes me look like a fool. Being corrected helps me look less like a fool in the future.

Actually, the word you're looking for is "unethical", not "immoral".

You just said online writing should not be judged on grammar. Why then would it follow that there exists some moral imperative to correct it?

For what it is worth, I used to feel the urge to correct but as I have grown wiser in my years I now see many people smarter than me use grammar in ways i do not. Now i see people who correct others grammar and spelling as pedantic jerks.

There is no authority over the english language. Your set of grammar rules are certainly different from virtually everyone else.

>People use grammar to judge your education and intelligence all the time.

You really shouldnt judge others; like ever.

>And so it would seem that failing to correct someone else's grammar online is not just unhelpful — it is immoral.

So you're saying correcting someone's grammar is helpful and moral?

Nobody is stopping you from doing this of course. If you believe it is moral to do, then do it.

> That's why they don't want you correcting other people's grammar online — it threatens a signal they rely on.

Who is “they”?

I judge people based on whether they get their point across -- you don't know the age or national origin of the person posting, for all I know I'm speaking to someone much younger than I who speaks more languages than I do.

I do judge spelling errors harshly, since most modern OSes will give a nasty red squiggle.

Anyways "immoral" is such a strong phrasing. Killing someone is immoral.

Letting someone argue their point badly is... well, I was raised Catholic so lets use that lens: Catholicism would refer to it as a "venial sin" -- you won't be going to hell for not correcting someone's grammar on the internet.