Simple. Screen real estate is the limiting factor.
I’m not going to repeat the same old arguments here – I’ve been running Linux since the mid-1990s – but you can run the Windows app successfully on Linux. I tend to use this only when I need the additional functionality unavailable on my phone. It is stable, and easy to install.
These instructions also work with Ubuntu 24.04 LTS – just substitute oracular for noble – and most likely earlier LTS, too.
IDK whether Roon thinks there is a large enough user base to warrant a dedicated Linux GUI. However, I think it is unlikely while Roon runs on .Net, so we may have to wait and see if a new development stack is used in the future (ARC doesn’t use .Net).
But even then, I can only see them supporting, say Ubuntu-based distributions running Wayland, as there are simply too many flavours to provide support for all. I don’t think Flatpak is an option either, unless they decouple the GUI and server, which seems unlikely.