Celebrities say they date other celebrities because they have the same job. But I think they just like dating famous people. Celebrities attract each other, like cattle.
The Simpsons can go anywhere in the world and not worry about any budgetary issues. However, even when the show has had its run, I think the characters can go on in perpetuity.
For somebody famous, it's weird anyway to meet someone, because they have a preconceived notion of who you are.