There has been no change to the blocking system on GAG. If you're using mobile though, the placement of the block function on user profiles was simply moved. Just click on the overflow menu (3 vertical dots in the top right corner of their profile) and you should see the option to block the user.
Blocking is mostly used after a final insult so that the insulted person can't fight back. It's pathetic why many people use it. Mostly only because they don't want to bother really understanding the point the other person wants to make.