It has nothing to do with the speed limit. It's unsafe and disruptive driving if you're intentionally getting in the way of others who are having to brake and/or take evasive maneuvers to avoid you.
Yes, it does have to do with the speed limit. Yes, it's unsafe if people are having to brake and take evasive maneuvers, but if it is because they are going way beyond the maximum allowable speed, that's their fault. Trying to put blame on the person who is going as fast as possible under the law rather than the person speeding is ridiculous.
Oh good grief. If you're having to brake or take evasive maneuvers, you're blind. It would be different if they were cutting people off, or slamming on their brakes. But if they are driving at a constant speed on the highway and you have to "take evasive maneuvers", you have your own personal problems.