Django and other web apps pale in comparison to Python's dominance in numerical computing. Im not saying they are not important, in fact I believe Python's use in areas other than math drove its adoption in the scientific community, and that one growth fed the other, but without ML there are far too many competitors to Python. However, almost everyone agrees thag py2->py3 was a mess. I like that when I run CL code written 10/20 years ago, and even older!, I dont have to worry too much if it is going to run today