Increasingly I see Sonus systems with a sound bar, sub and, maybe, rear speakers rather than a receiver system. With that, turning the TV on fires up the Sonus system. Then, for music, you control your Sonus system with your tablet or Alexa. My MC library becomes the source for the Sonus system, not the playback system. And Spodify and Tidal and Amazon Music increasingly become the source.
Harmony built their business on relatively simple systems, not systems like yours or mine. Those people are increasingly using Sonus, Smart TVs, Alexa etc., which eats into Harmony's business. Without a Blu-Ray player, people just do not need a Harmony remote.
IR remotes are still the best for sophisticated systems. But, the lower and mid-range folks are just not as interested in the remote anymore. It no longer controls everything, so they use the cable remote, Alexa and their tablets. How does the average user control Spodify, Amazon Music, Tidal, Sonus with a Harmony? Once you cannot do everything with the one remote, it changes the game.
I have 2 fully tricked out 7.1 systems, with dedicated 7.1 amps, etc. And a 2 channel system with tube equipment and a nice DAC. And a vinyl system. And the lights are controlled by the remote. Popcorn popper is still manual, however. Those type of systems deserve a dedicated remote, although I would argue that Harmony is not the best for that type of system. But we are not the norm.