Sure.
1st their effect are extended to all the state. Aristocrats improve RGO output, Capitalists improve factory output both of them allied with RR are sure profit.
The clergy depends of with kind of gov and pop you have, they lower consc and/or mil from lower strata pops. So if you don't care much for them, it's good help to control revolts, but if you have a SUPER-democracy going with a lot of benefits, make them work too.
P.S.: Clergy are mostly needed in colonies