Agreed I used to fly all the time. I’d swap seats no problem if it was for a good reason, like allowing a couple, or friends or family to sit together.
I won’t do it so friends can sit together, but I consider it if it is a young child. Not a teenager or sub-teen, but a child. Also, if it is an elderly person who needs assistance.
A teenager or sub-teen should be independent enough to sit on their own.
And I am not going to do it so a couple of friends can “hang out” together. Or a husband and wife. I think it is rude to even ask, unless it is a young child or an elderly person who needs assistance.