Eh. I think it's just the instinctual assumption I make when I know a celebrity must be a certain age and I haven't seen anything about them in awhile.
Take Twilight Zone, for example. Aside from Shatner, Billy Mumy and Robert Redford, I've basically assumed that everyone on the show is dead now.
Oh, what's that, America? You love Chris Pratt? Well, I guess we'll have to wait and see the overnight ratings for this upcoming season of Parks and Recreation for me to determine how full of **** you are about that.