The TIDAL app is just part of TIDAL, and TIDAL clearly is essential, Roon not so much, I’d say. After all, a software unfold is really just another manufacturer, and there are a lot of those, now, and the process is getting less expensive to incorporate (with the ESS chip and the XU216 firmware). Roon is certainly more influential than most, I’d think.
One of the points the book makes is that it’s important to keep your support coalition, your influentials and essentials, off-balance. To keep replacements for any disloyal members waiting in the wings, clearly visible. If Warner Music recants, for instance, they could go to UMG or Sony. If TIDAL recants, they could to to a different streaming service, or even start a new one. It’s not clear to me there’s a good replacement for Roon, but maybe JRiver or Plex would suddenly grow MQA capability.
This is all assuming MQA Ltd wants to dominate like Dolby, of course. Perhaps they don’t.