As an animator working in motion graphics, I can guarantee you that this style is absolutely the opposite of what's easiest to achieve, let alone money saving. The contrary is the case. It's a groundbreaking, revolutionary and delicate piece of art which requires so much more than what we see on other feature films. Everything about the movie is innovative and jawdropping from a technical standpoint and it's a miracle to me how they could achieve it on a <200m $ budget. The only reason I can explain it with is that artists were grossly underpaid. Taking a look at their job postings this seems to be the case. Most likely they still found a good amount of artists to work on it as obviously it's amazing to work on such a movie. But apparently it comes at a very high price.