Witness is different from node operator, but maybe many run both? I'm not sure, nor do I know in detail. @josephsavage has mentioned starting a node a few times (I think; forgive me if I'm wrong about that, Joseph) so maybe he can give us some insight.
Anyway, that's interesting that it comes down to one piece of software that most people don't run. I wonder why it depends on that. I've never really used the favorites feature before. I should explore it.
I don't think the favorites list is for everyone. It can keep you from seeing certain things if you live there. Like I said, I realized I need to venture out a bit more. It's super useful for catching up on key people when you are off chain for the weekend or a given amount of time.
I have indeed thought about it a few times. Most of the top witnesses also run full RPC nodes, but it's not required. If I ever run a witness it would be to run a node and try to capture a little value for it, so it would be both.