Radical Theory
Someone posted the following theory on Twitter, and I can totally believe it: The Flintstones and the Jetsons live in the same time. Not the same timeline, but literally at the same time in a dystopian world. On the ground where the Flintstones live, the collapse of society has made it seem like prehistoric times, but the Jetsons are part of the 1% and live in luxury in the clouds.