Why do people expect you to discuss their essays?

I’ve seen so many people (including myself) just make brainless, simple comments. Then in comes the big brains with their 20 000 word essay, which nobody asked for （￣へ￣）
Then will get upset and become rude when the OP doesn’t want to read/discuss it??
I’ve seen it so often as well as it happens to me

someone explain plz
(yes i just got done arguing with one of those fcks and i am annoyed by it)(〜￣△￣)〜
Shit lemme read in peace