When vinyls were the predominant media form, it was prohibitively expensive for most artists to press a master, cut vinyls, package them, market it, and distribute it. I can do all of that in 10 minutes with Spotify now.
Tapes made this a little bit faster. And then CDs made it a little bit faster from there. And then MP3 players made it quite a bit faster. And then download speeds and prevalence of internet made streaming possible, and it made it a LOT faster. And then here we are - about 10 years after the emergence of Pandora and similar services.
To use your example: Elvis had a TON of funding and was able to maintain that rapid release cycle while touring because of that. Smaller DIY artists don't have funding, they're all working jobs, etc...
There was plentiful work for pianists and organists in movie theaters before the talkie. And so forth. Musicians have faced a constant back and forth relationship with technology practically from the git go.
Not sure if this is intentional, but it's a great HN style eggcorn.
I have a lot of my grandparents old records, and when I first went through the collection I was surprised at the output of some artists both big and small. The obvious example would be Elvis. Just counting his studio albums, the guy put out over 20 albums over his career 24 year career, and that isn't counting singles, soundtracks, or whatever else he put out. If you factored in all of that, it's easily in the range of 150-200+ releases.