How do you know they were trying to prove a point? Did you ask them? There are a lot of crazy cyclists on the road, sure - and there are also a lot of crazy drivers. I think very few drivers are 100% aware. (I think few cyclists are 100% aware also, but the average cyclist is more aware than the average driver)

As for a "respectful exchange of right-of-way", that can be very difficult even when the cyclist is respectful, because many drivers don't know the laws regarding right-of-way. For example, if you are in a car, and you're approaching an 4-way unsigned intersection and a bike is approaching from the right. You get to the intersection first. Who has the right-of-way? (Answer: the cyclist. It doesn't matter who gets to an unsigned intersection first - the traffic on the right has the right-of-way if it is a 4-way intersection) How many motorists actually know that? How many motorists properly negotiate a busy 4-way stop? I know when I drive, many motorists at 4-way stops ignore the proper order and cut me off.

I think your greater point is that all road users need to be more responsible, and if so I agree completely.