I see it as valuable and useful if someone respectfully corrects me or disagrees with me, unknown or not, both in real life and online.
Sometimes it may be the point of a conversation for me, to exchange different opinions, to get to know the other person through that, and to learn from corrections of things I got wrong before. I am grateful for this.
I read your suggestion to instead block you, but I don't see why I would want to block you, or anyone else for that matter.