If you already have a lot of domain logic in Python for your backend, that would make it easier to write a frontend living in the same codebase. (For example, imagine a framework for autogenerating forms for your Django models; this already exists server-side, but native client-side Python would give you more options. And if your framework owns both the client and server, it could autogenerate the API so you don’t even need to write one for happy-path usecases.)

If you are already using Python on the backend, not having to hire/train a completely different skill set/stack is appealing. Sure, the browser and CSS/HTML specialism is going to remain, but not having to split your team by JS vs <backend-language> would make it much easier for a team to collaborate and share work.

I think Python in the browser only has to be “almost as good” in a direct comparison for it to actually win out as the best choice organizationally for many teams.