So many people are afraid someone will interfere with them on purpose if they "indicate" what they plan to do.
It's true too.
Have you put your signal on before and had someone intentionally try to get in your way. (like speed up to keep you from being able moving over)
If I had room and put my signal on and they do that I move over anyway.
Then they act like you did them all kinds of wrong, because the same person that tries to get in your way is the same kind of person that gets all pissed about it when you do it anyway and they couldn't stop you.
THEY put themselves in the way even though you had room and signaled. (piss on em)