For the most part artists keep to this standard, but on some cases like Crayon Shin-chan proportions are completely disregarded such that the characters resemble some Western cartoons.
Even Miyazaki himself, the harshest Disney critic at Toei, enjoyed the Fleischers. Especially in the quality of animation. For example, films such as Ghost in the Shell and Megazone 23 were both experimental and would end up having a strong influence on The Matrix.
Not only are these stories interesting and engaging, but some of them will even leave you an emotional wreck.
Oswald made a brief appearance after Alice in Cartoonland, but Disney was forced to give up the character to Walter Lantz. Whereas in Japan cartoons are targeted at children, teens, and adults alike.
In some ways, I think it is more limited than American animation, in terms of character designs, of art style or with the inclusion of certain elements like a beach episode and the like.
As a result of this many studios went bankrupt and were closed. I'm not counting the works by Pixar since Disney unfortunately bought them in To summarize, due to the decreasing quality of animation in American cartoons, as well as the decline in quality storylines, and a falling age for the target audience, America will slowly lose more and more of the entertainment sector to the Japanese as more and more quality anime is made.