Not really no. It's possible for pathogens to be transmitted, but the likeyhood is so small that we don't bother. Unlike fish where NOT quarantining is just stupid.
Oh God, alright, confession time. I've qt'd many crustaceans. Never had one "go bad" on me in QT, either, call it compulsion. I have to do it that way!
1 reason I have heard for QT'ing EVERYTHING is the (very remote) possibility that a pathogen could be brought in on the shell of a crustacean or snail for example. Most parasites have a phase in their life cycle where they are attached to something solid. That period usually is fairly short and would be interrupted by even a short QT. Because of this I have recently started QT'ing everything with 1 week for low risk animals like shrimp.
Allen