Debate over the best sounding player software has existed since digital audio playback became more mainstream. Roon is just another contender in the game. I suppose its popularity has made it an easy target. I don't see nearly the same discussion over the sound quality of Lightning DS, Lumin OS, Aurender Conductor, and other proprietary software.
What is more agreeable is that Roon is one of (if not the best) library management tools available. It seamlessly allows a user to access both local media and streams from Tidal and Qobuz in an elegant and user-friendly way.