It is more dangerous to be slow and have people constantly merging in front of you, rather than be slightly faster and not have all the merging. Accidents happen when vehicles are going different speeds, all things equal.
American road laws are insane here. The law should be simple; you must be in the outside lane at all times unless you are overtaking, and once you're done overtaking, you should merge back into the outside lane.
This is dangerous nonsense. It's basically just a justification people find in order to feel good about their unsafe driving.
That seems like a surprising enough statement to be backed up by data. What is your source?
Everything I've read points toward larger margins of safety (longer distances, slower speeds) being safer.
See e.g. https://publications.lib.chalmers.se/records/fulltext/252480...