Short - you are so on the money with this observation, about letting it go.
I think that was part of what I was getting at with my post on attracting control freaks. I have learned to let it wash right over me. If you engage, then you are part of the process, but if you disengage you can watch the behaviour. You are right - there is no mileage in winning if the other person isn't engaged.
It isn't the same as being a doormat - I just choose now what I am going to take a stand on, if anything,
that is the power of 'I am sorry that you think that way' you aren't engaging, you aren't disagreeing, but neither are you dismissing their feelings.
I am interested in the truth, but only in debating with someone who shares that interst, not with someone who wants to score points, and 'win'.