That seems very dangerous, sometimes you need to accelerate a bit to avoid an accident.
Other drivers around you are going to expect you to be able to accelerate past the speed limit during dynamic driving conditions like heavy traffic, especially on the interstate. This will make some people unable to drive in a predictable way in some circumstances.
One thing that people underestimate is the danger of deviating from proper right-of-way. Letting someone go that is supposed to yield to you is an example of this. All of the drivers around you are going to expect the other car to yield, and for you to go. If you do the opposite to "be nice" and stop when you have right-of-way the other drivers around you are not going to expect you to stop the flow of traffic. It can cause confusion and that leads to accidents.
We call them "niceholes". In Portland, it's a major problem.