centrally-unplanned:

Some “invented history” in animation for you: If I say “The Flintstones” your brain immediately fills in “The Jetsons”, right, as two parallel cartoons time-swapping the postwar 60′s nuclear family? Its technically true, The Flintstones first aired in 1960, and the Jetsons in 1962 - except the Flintstones aired for 6 seasons and 166 episodes through its original run, and was incredibly successful, while the Jetsons was a flop, cancelled after one season and 24 episodes. 

You only remember the Jetsons because while it failed in its primetime slot, it got some sleeper success on syndication in the Saturday morning cartoon slots in later years, giving it enough cultural currency for Hannah Barbera to revitalize the show in 1985, producing 50 additional episodes over two seasons, plus specials. The large majority of The Jetsons’ content was made in the 1980′s, including key staples: Rosey the Robot, for example, barely ever appeared in the original, but is a core cast member in the 1980′s version. 

They also were different shows: the Flintstones was in fact a prime-time airing show aimed at adult audiences, the first cartoon to succeed in doing so. The Jetsons tried to be that in intent but failed, instead finding success in kid’s Saturday morning slot, and the 1980′s reboot reflects that. Audience tastes however had changed by the 1980′s, and Hannah Barbera owned both shows, so in the 1980′s they aired them in similar blocks for similar audiences, and that is where things like The Jetsons Meet The Flintstones (1987, 20 years after the last Flintstones episode was made) comes from. Their connection was real, for sure, but only became solidified over a 20 year gap, and most audiences who saw The Jetsons saw a product of the 80′s, not the 60′s.