Hard disagree. If you compare the quality of work in Gravity Falls or Hilda or Rick and Morty or even Spongebob Squarepants to the made-for-TV animation of the 60s, 70s and 80s it’s really no contest.
Hanna-Barbera didn’t dominate Saturday Mornings because they made great cartoons, they dominated Saturday Mornings because they perfected the art of cutting corners and were thus able to produce cartoons quickly on a TV budget.
(No offense to your namesakes.)
