Michaels explained during his keynote address at a Cannes Lions advertising event in France (via Deadline) that when SNL launched in 1975, the goal was always to be attractive to audiences around the whole country.
As Lorne Michaels said, many shows now are subject to “narrowcasting,” where programs are tailed to specific audience demographics rather than the general public at large.
Saturday Night Live has been around for a long time, and was created in an era where television was different, to put it lightly.
(Well, those that would be allowed to stay up late to watch it, obviously.)