Before Disney, you could find a whole variety of animation styles.
Disney was established in 1923. Animation was in its infancy. Filmmaking was in its infancy. Such a statement needs clarification.
But the vision of Disney was to make everything round and smooth and beautiful. Every animation cel was to look like a masterpiece portrait -- because that was the general populace's desired art at the time.
Citation needed. Disney has almost ninety years of animation history with a range of divergent styles. I can't say what 1920's American looked for in its art, but I can certainly say that animation was a novelty at its time.
And that's what Disney was trying to make, animated art.
Again, citation needed. And also clarification ... Disney the company? Disney the man? Disney the man started making shorts such as Steamboat Willie. 1928. The point of this short wasn't to make art, but to entertain. Disney the company has been making a range of animated films for years of many different styles. All can be described as "art". Even Steamboat Willie.
You might have found a sharp edge on a villain like Jafar in Aladdin but the main character would be round and warm.
Now we are in the Eisner era. This needed to be noted at the start of the argument.
Others tried to mimic the stylings and it became a de facto standard mostly because it sold.
What others? And seriously ... do you think Disney was the first to use lines, curves and edges as a way to depict stylistically character? That's a ludicrous statement which needs a citation.
That's just the first paragraph. It may make great banter for cocktail parties, but it means nothing.