Avatar: The Last Airbender

Are we watching the same show?

sloppy, really low frame rate

It's no Lion King, but I wouldn't call it sloppy. The animation is simple, that's true. But it's funny you mention anime, because that's a typical anime problem, with often still images with only the mouth moving. That's because it's faster and cheaper, so they can focus their energy on the fight scenes. If it bothers you here, it should bother you in anime.

poorly drawn

Again, I don't know what you mean. I'm literally watching the show as I write this. You can say that you don't like the art style. That's your personal preference. But poorly drawn just seems objectively untrue.

for the time, it was poorly animated

See, I would argue that modern shows are often poorly animated. If you compare earlier Simpsons episodes to newer ones, you can see a clear difference. I believe it happened when they switched to computer animation. The new stuff is cleaner, with a higher frame rate, but imo lacks the soul. There are probably countless of examples. Spongebob would be another one. Again, the show is not the pinnacle of animation, "poorly" is just not the right word. If you want to watch an actually poorly animated show, just watch Invincible.