Sure, this is possible, but I'm not basing my concerns on headlines so much, but rather what I'm seeing out there when I try to educate myself on what is going on in the frontend world. Once you get past basic JS and JQuery, everything seems to just take for granted you are using a toolchain that doesn't leave much room for Python.
All of the skeletons/starting points out there pretty much ignore the fact that backends exist in general (by making demos just github stargazing or whatever, or using firebase/<insert graphqlaas> and such). It's definitely not the case that you need explicit nodejs on the backend, and that's not the common case for a lot of large companies. There are tons of options.
Render services [1], Sidecar processes [2], not-doing-universal-rendering, or just running a simple universal nodejs server with an entirely separate API backend.
Integration is not typically that difficult. It takes a day or two of sitting down with docs and intentional effort, sure.
Worrying about wasted effort is silly though. The amount of choice these days is crazy, and web development lately is mostly hype-driven, though it doesn't really need to be. We end up solving the same problems over and over again with a slightly different set of technologies (which has it's good notes and it's bad notes).
For many companies the backend is several orders of magnitude larger than the frontend (hundreds of separate backend services/daemons/etc in any variety of languages), so optimizing the whole stack for the sake of the frontend would be nuts
