Lots of applications used it. I recall Wacom having some art applications made with it, I remember League of Legends used it in the early days. The link you sent also specified quite a few uses.

But most notably there is a focus on desktop/mobile applications when the real dichotomy ended up being web/mobile applications and a ton of internet companies were dumping money into their own frameworks at the time because who wants to pay rent to Adobe? If artists don't want to pay for their proprietary crapware, imagine tech companies.

AIR was yet another closed platform to throw on the pile of failed closed platforms.

AIR apps were the Electron of its day -- slow, poorly-written HTML/CSS/JS (well technically AS but linguistically similar enough) garbage, which reuse exactly zero of the affordances your OS grants you, on top of a runtime that was waaaay too fat for its own good.

Mercifully, I only had to interact with a few AIR apps, and by god it was a terrible experience. The platform itself may have been fine but it was definitely the target platform for people who think of dev teams as cost centers and not value creators.

AIR was wildly popular for making games and cross-platform applications around 2010. These could even be submitted to mobile apps stores, even for iOS.

But AIR produces packaged applications you need to install, and not the embedded-in-a-webpage experience that Flash was.

A shocking number of "native" applications are actually Adobe AIR. Brawlhalla on Steam (one of the top F2P games) used AIR as of a few years ago and still might! (They use a HAXE-based client on consoles)

I wrote a good number of AIR apps back in the day, the reason it didn't succeed (and why electron has succeeded) is because Adobe didn't want to allow devs to bundle standalone .exe/.app releases. You had to install the air runtime permanently alongside the application you wanted. Nobody likes 3rd party dependencies that worm their way into your system, just cause you want to run a simple app.

I have an old version of the Pandora AIR-based app that I'm holding onto for dear life. It still works wildly better than any of the subsequent UWP or Windows Store apps.