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...
We don't live in an ideal world, and having a bunch of cars merging in front of you definitely makes you less safe than having a static situation. I try to make sure I can see through/around the car in front of me, so that I have advance notice of what's happening down the road.
For example, the specific law in California: https://leginfo.legislature.ca.gov/faces/codes_displaySectio...
Still, I tend to find that people underestimate the danger of short distances. Often it's just better to accept a 100 cars going in front of you than to shrug off following someone at 1.5 seconds. It can go well for years because crashes are rare, but when you are in a crash you will be royally screwed when you don't have the reaction distance needed.
Simply put: follow distance is not a unilateral decision.