The issue is that when you slow down, you’re (a) creating ‘turbulence’ in the traffic flow with increased speed differential between cars and increased lane changes, which increases accident risk for everybody, and (b) it’s not even solving the problem because you still perpetually have some impatient driver wedging themself in directly in front of you, deleting your buffer zone.
It’s safer to drive a little closer, keep up with other traffic and defend what gap you can in front of you.
Agree with your conclusion here, though. The best response is to simply not drive in this kind of traffic.