I normally just surrender when I know I have lost, even in FFAs and no one really cares
I don't think you are accurate. I suspect many people care. The person who was in the lead before your surrender but suddenly isn't b/c your neighbour gains your lands for free and now jumps to the lead almost always 'cares' about your surrender. Not complaining != doesn't care. It is indeed annoying when the whole dynamic of an FFA changes b/c 1 person surrenders. Even worse when someone gifts their territories to your enemy and then surrenders, or just decides to randomly help 1 player win and then surrender, etc.
But it is an FFA after all, sooooo anything goes. Nice/mean/slimy/deceit/gentleman tactics are all in play. Whiners will whine, many will cry Unfair ... but so is life in an FFA.