Personics - iTunes In The Analog 80's

In the late 80's, cassettes were in. LP's were on their way out, as were 45rpm singles. That meant that there was no longer a way to buy a single song you wanted (cassette singles - or "cassingles" were still a few years away).  Personics was a company ready to fill the gap with their kiosks in some major record stores. The machine would let you create a list of your own musical selections (the machine also let you preview a few seconds of each song), and 20 minutes later the clerk would hand you your own mixtape with custom-printed label. Check out the the TV commercial.

Once 45's disappeared, it really wasn't until the dawn of the internet that it was easy to buy a single track of music. Of course you could make mixtapes before this, but that meant having access to all the albums with your favorite selections on them. The Personics was an interesting idea, but I don't get a sense that it was ever very widespread. It hit some larger music chain stores, but I personally didn't see it all that much. The ad I've included at the top of this post cites sales of over a million songs, so why didn't the service stick around longer? Why did it take until the introduction of iTunes only a few years ago for the model of buying individual songs to finally work?

related:
Rebirth of the local CD store
Mix tape memory stick
Origin of the audio cassette
Stylish Ampex Micro-24 cassette recorder