In a purely moral dimension, it's hard to disagree. On the other hand from an environmental perspective the best thing to do with a car is to get it up to speed as soon as possible and keep it there to the journey's end. Cars that repeatedly slow and idle use their resources (brakes, fuel, etc.) less efficiently, and emit worse fumes. This is of course somewhat mitigated with electric cars, but not entirely.

On bike or foot, I especially hate to see the one last car in a line slow, stop, and wait for me. It would be less polite perhaps but big-picture preferable for them to just keep rolling.