The issue is when it is done publicly, it is almost always done in bad faith to try and shame/put someone down and dismiss everything they said due to a mistake. If you want to teach someone you should send them a private message. Don’t put them on blast in front of everyone. It shows a lack of empathy and depicts you as someone who wants to appear superior/better than them. Of course, there are ways to do it publicly but courteously, for example something like “just fyi, it’s they’re not their :) but anyway, I do agree with what you’re saying [or] it was interesting to read your take on this”