to be fair, the 70s were a pretty weak era for animation.

The 1950s, 1960s and 1970s had good cartoons, but overall, it was a big downgrade compared to the Golden Age of Animation from the 1920s, 1930s and 1940s.

The main reason was television, older cartoons were shown on movie theaters, not television, when cartoons moved to TV, they had less budget and shorter schedules, Hanna-Barbera thrived in that era because they knew how to deliver something watchable with little money.

The 1980s helped thanks to Ronald Reagan, because laws over child advertisement were less harsh, and most cartoons from that era were made to sell toys, but it helped cartoons get better animation and budgets, then the 1990s is when cartoons greatly improved with them being creator-driven.