Ever since Dulles was built, there’s been a struggle to actually get people to use it. DCA is just so much more convenient. I’ve heard from people who were around at the time that it was virtually a ghost town when it opened, and was a great place to fly small planes since there wasn’t much commercial traffic. Even today, the two airports serve about the same number of passengers per year, despite Dulles being approximately eleven thousand times larger.

Personally, I use DCA whenever I can. It usually takes me about fifteen minutes from car to gate. Dulles takes ages and ages, since everything is so far away.

A lot of the rules are just trying to get people to use that big expensive airport more.

Most members of Congress don't care about the perimeter rule (if they are inside the perimeter) or hate it (if they are outside the perimeter). That's why there are exceptions now.

The rule still exists because local jurisdictions really really want to keep it, and getting rid of it is just not worth the fight for anyone else.