I think there's enough said already on topic, but I still wanna share my point of view.
TheSafePlaces wrote:1. Why use Linux and FOSS?
Freedom.
Because I can get it for free or for any price that satisfies me. Because I can tweak everything about how my OS/software behaves, how my desktop does look and interact with me, what software and services I have and what are banned on my machine. Because it's really secure once you set up a firewall and proper file permissions. Because it's easier to communicate with FLOSS software developers than with commercial ones. They respond faster, they are glad to know you supported the project with a small donation, they can add functionality
you need on a paid basis (that's actually how any big FLOSS business works) instead of leaving you with “maybe we'll implement this in our future release in 2035, thanks for interest in our product”. And, which is kinda funny, FLOSS software is often better documented.
TheSafePlaces wrote:2. And, separately, why use the same for pro-audio?
Again, freedom, overall cost, and great tools also.
Because there are FLOSS Ardour and Cadence that turn my workflow into simply opening a DAW and recording. Because Linux kernels can be realtime- or lowlatency-patched, which gives a better environment to work with audio. Because non-free Harrison plugins are more affordable than most of Windows/Mac plugins, while they are of very high quality: no crashes, no glitches, no CPU overconsumption.
TheSafePlaces wrote:And lastly, 3. (similar to, but subtly different from, the second one) - What are the benefits enjoyed by pro-audio users of Linux over Mac and Windows platforms?
Flexibility and stability, ease of setting things up.
While it's usually very tricky to set up a Windows DAW to work reliably and without dropouts (not the case with Mac, it's also very nice in that regard), Linux setup requires just a little bit of JACK and Pulseaudio configuration, kernel replacement (if needed), and that's all. Really. Open a session in a DAW, plug in your instrument, and make some noise. No need to deal with ASIO driver setup, no need to struggle with those stupid soundcard control panels. Linux package management is breeze: once you install all your software of choice (and this can be done in one console command or via selecting a couple of corresponding metapackages), everything updates fast and from one single point, no need to fight with autoupdaters and other CPU/RAM hungry garbage you deal with on Windows. No need to wait until Windows finished its enforced (and very time consuming!) update which you didn't even ask for. Also, no iLok or other invasive and restrictive stuff you are forced to use if you want to work with the best software solutions. There are ready, all-loaded multimedia distributions like AVLinux and KXStudio, which don't even require fiddling with external software sources. Just install that, set up JACK for desired latency, and get straight to producing your hits. No need to spend a day or two just to download, install and configure all the stuff you need. You'll be up and running in a couple of hours, if not even faster. Once it is set up, it works until your DAW computer dies or gets replaced. Hardware upgrades are easy also: you won't lose your license activation if you buy a new CPU or replace a motherboard because the previous one suffered from, say, a thunderstorm.