It might make me sign my work a bit more (since I kinda don't do that), but I'm not completely irritated. Usually, I mirror my Instagram posts on Twitter and the like, so these pictures are posted everywhere under my name.
I don't really condone these types of practices, since it can make it easier for reposters to steal artwork and claim them for themselves. But, all I can do -- outside of catching potential reposters -- is mirror my stuff to all of my sites so that there's really no need to. It's kinda why I post my Patreon art 2-3 weeks later on the main sites. People who pay get to see it earlier than most (along with some sneak peeks), and then everyone else sees it. I don't lose money, and there's no need for someone to try and steal because...well, I've already posted it later on.