I've been thinking about the "As you know, Bob" trope

It's never "As you know" or "As we all know" or anything else like that. It's always referred to as "As you know, Bob".

Are we supposed to think that Bob does not remember his own name? Does he need frequent reminders? Should we be concerned about Bob and his inability to remember things like his name, recent events, and how light switches work? And if that's the case - should we really be making fun of him like this?

Or maybe we should just be glad that Bob gets the support he needs. As you know, that's not always the way it shakes out.