Actors aren’t, but actors which have “excessive amount” of components aren’t recommended as each component needs to be serialized etc. So naturally you use all the components you need, but you don’t want to i.e have a building and all the gadgets inside of it be part of the same actor.
Rather what I’m thinking is that if we have something like, an alarm, which has a static mesh, an alarm sound, and a point light, if I want them to be editable in the editor, I need to add all three separately in the editor and then add assign the references, instead of just being able to add the alarm component which then brings with it the other components.