Why do some facebook users worry about messages from "friends"?

[Sanford]

I see people worrying that their "friends" will know that they read their messages if they open it. Nowadays, when you open a message, it will say "seen". Some people don't want their friends to know they read it for some odd reason. If you don't like the people in your friend list, why add them in the first place or even keep them in your list? That makes no sense.
Instead of trying to dodge them, why not tell them you don't like them or want to chat with them? -_-
Example:

Man: Oh no! By opening this message, Steve will know I read it!

[OSnapItzChelle]

I honestly don't understand ethier.. For me though if someone reads it and they dont respond for a long period of time I feel like they are ignoring me, and I dont think anyone likes that feeling. I know it sounds stupid but I always feel like that when I see someone "read" my messege. Hoped this helped?