Do you know of any other way that the general public could have heard the content? Maybe I'm missing something.
It depends on the station or the market. Because NPR spent a lot of money creating new content for HD. I know for a fact that some CBS stations (particularly WUSN in Chicago) created original content. Clear Channel had its format lab working on stuff. But after waiting years for consumer radios to be available, most of the radio industry had moved on to streaming. People already had phones. No need to wait for electronics manufacturers to make them. They were already in people's hands. The HD window of opportunity had passed. The loss was iBiquity's.
Did I say that? No. If you go back through these boards to when I joined, I've always expressed the view that any new service that required the public to buy new radios was going to be dead in the water. I feel the same way about DAB.
Well working backwards here, no, I have not gone through your entire posting history trying to glean what your opinion might be on this or that topic. I have a general sense of some user's opinions, but scrolling through past posts thinking "I'd better read up on what The Big A thinks about X before I jump in" would be...a little weird.
As for your (sorry I didn't see it before) opinion that people having to buy a new radio was what killed the beast, I would counter that this has happened before. FM required everyone who wanted to hear it to buy a new radio. Everyone who wanted to hear that sweet CD quality sound had to buy not just a CD player, but replace a good portion of their music library with CDs. The VCR was replaced by the DVD, the DVD was replaced by the Blu-Ray. And as I alluded to earlier...video game consoles.
And while it took awhile for the equipment to get to market, they are on the market right now and have been so for quite some time. My rickety old 2016 car has an HD radio, and just this morning as I was sitting in the drive thru at Whataburger (the one near me is very slow) I was flipping through the various HD2 and 3 offerings of our local stations. "Oh, this one has Dan Patrick's show! Where else could I possibly find that?!" I didn't have to buy any extra equipment. The car already had what I needed to find out that HD2 and 3 channels aren't worth the effort. *
And yes, phones came along, and streaming services, and those things have made HD radio irrelevant for the most part, but that's happening for FM as well. In another thread it was pointed out that AM radios are starting to disappear from some cars. I have pointed out on a few occasions that younger people today don't even think of the thing in the middle of their car's dash as a "radio." For them it's the "infotainment."
Yet for a moment, there was a chance that HD radio could have had something to offer. Yes, the radios weren't ready when the promotion started, but when they were (and they've been available for a long time now), there was nothing of value on them. Perhaps things would have turned out different if companies had put more effort into them, but more effort is something the business gave up on long ago.
*I listen to The Wow Factor on the HD radio because the signal and sound are better.