There is no dominant framework because there are manny good ones focusing and different things. That is because nodejs is larger than anything we've seen thus far.
What framework might you use if you had to build a multi-vendor marketplace with hundreds of forms and only 1% of the form fields require JavaScript for interaction? Would Django be a bad choice? I don't have experience with Django, but I have experience with Rails and Node.js, and I would pick Rails over Node.js for such a project without any hesitation.
So I'd say Django gives you some tools to implement large forms but don't necessarily is a big advantage compared to something you might find in node or ruby
Some people do still build apps like that – but they have no need to use Javascript for it, as it adds no value to their architecture. So they keep using Rails and Django, and don't waste time on making a JS framework instead.
Also Django was created at a time when AJAX was at its infancy. Most apps needed to generate HTML and the server side had to include templates, routing, authentication, etc...
More modern applications rely a lot more on client side code for routing, and HTML generation and the backend is mostly an API for a non-relational database. Plus a lot of other services for random things like Auth, caching, etc... To the point a lot just opt to go serverless and connect directly to a Firebase for storage for instance.
Django doesn't feel so at home in those "newer style" apps. Most features go unused and the ones you want don't have great support and you have to rely on other tools such as django-rest-framework. If you want to use a NoSQL database, then the nice ORM goes out of the window and you usually lose the Admin interface.
So in other words I think a Javascript Django would have very low usage, because people just don't build apps like that anymore. People prefer light backends reliance on external services and more specialized data storage options. So they want something that is lighter, easier to deploy and scale.
The only reason I still would use Django today is the amazing Admin interface you get in exchange for using its ORM with a relational database.