There were no discussions on HLTV when the block function was implemented because it wasn't being used correctly by certain users, no user should have that power on HLTV.
Users were blocking each other simply because they disagreed with their opinions, the only way to contact these users was to PM them or to post on the guest book.
Despite being blocked, they could not see your posts but you could still see their posts, leading to confusion and lots of threads being made specifically to speak to certain users because they felt they were being unfairly blocked.
No discussions were being had because users were scared to even have a heated debate otherwise bang -- blocked forever.
A truly awful feature that directly negates the entire purpose of a forum.