I agree in isolation, and I have used nest-asyncio a couple of times where it really was a lot easier than the alternative, but from an ecosystem perspective I'm glad it isn't the default. Most of the time someone wants to do this it's a junior trying to work around a non-issue (e.g copy-pasting from a guide that includes asyncio.run()), and the trade-off is a massively increased surface for performance footguns throughout your code base and all the libraries you use. Linters could save you from the first case but it would be a lot more work to profile, track down, and fix spots in all your dependencies that cause your event loop to get fragmented.