You're kinda restating what OP was pointing out. People don't understand following distance, so they will merge in anyplace there is physically room to do so, regardless of whether they are leaving adequate following distance.
I agree, it's infuriating when you're just trying to maintain a safe distance in a line of cars passing in the left lane, and some dipshit comes flying up in the right lane and squeezes into the buffer of you. But that's on them for being an entitled prick who doesn't get (or doesn't care) how safe driving works.