I.e. The transmuter's #1 contribution to group/cabalmates is metabolic quickening and not enlarge/reduce/fly or even slowing opponents as there are other sources for doing all of that without having a transmuter handy.
or
Healers are mostly* useful for sanc and (to a lesser extent) in combat healing (depending on class). Everything else I can get elsewhere without having to deal with a healer (who is probably incompetent)
I would argue yes, and that this encourages the Rambo mentality by making it possible in a way it wouldn't be if class skills weren't available in non-prep form.