> Hence I said "at best", meaning, in the best case scenario some FOSS
> tools may be functionally equivalent. I think the exception might be
> JACK, as the case could be made that it is functionally superior to
> any other inter-application audio and midi routing framework.
as good as JACK is, it's a little bit of a red herring.
JACK needs to be as good as it is for any linux audio to be worthwhile. when you have lots of things doing seperate jobs then yes you need something like JACK to be able to deal with it all.
proprietary music software such as cubase/ableton live/protools doesn't need anything like that. pretty much everything needed to work is available inside the main program or as a plugin opened inside the main program. for anything else rewire suffices and rewire is a hell of a lot easier to deal with than JACK, open the master program first then the slave and rewire is automatically engaged and routing audio/midi between both programs is available in the same way you would route tracks inside the program.
so if you have someone used to being able to work in such a way then they're going to find it very hard to adjust to a very different way of working.
time spent learning a whole new way of working could potentially kill any inspiration you have.