When is the last time you bought one? I've had iPhone 2,4,6,12 and a few iPads along the way. You?
I have owned three Mac computers: a Macintosh Classic, a Performa 5230, and a late 2009 Mac mini. My roommate received an iPhone SE as a gift and replaced it with a third-generation iPhone SE once its battery stopped holding an adequate charge.
If you're not an Apple user why do you care?
Unlike me, many of my audience are Apple users, as are many of Spotify's customers.
Exactly which market is being disturbed and in what way?
In the case of the featured article, the market for subscription music streaming is being disturbed by Apple forbidding Spotify to disclose the features and price of its subscription service to prospective customers.
What is the real world benefit to Apple users to have third party app stores?
The real-world benefit to iOS users is availability to stream works that happen to be on a streaming service other than Apple's own. Some albums are on Pandora, Spotify, Tidal, or some other service, and not on Apple Music. The typical revenue split for services like this is 30 percent for the streaming platform and 70 percent for the artist and their record label. Given Apple's requirement to use its in-app purchase system with a 30 percent fee in order to be listed on its App Store, this would leave 0 percent of revenue for any streaming platform other than Apple Music.
Another real-world benefit to iOS users is availability of applications in categories that Apple has forbidden on its App Store. Circa June 2009, one former example of a class of programs unavailable to Apple users was rereleases of Commodore 64 games on iPhone by the games' publisher, which Apple banned solely because the user could reboot the emulated Commodore 64 computer to ROM BASIC and then key in a program not approved by Apple. This ban lasted from June through September of 2009, when the developer worked around the ban by specifically blocking the use of the ROM BASIC prompt. From April to September 2010, Apple was enforcing a ban on transpiling applications written in other programming languages to Objective-C or C++, which made ports of games using Lua or Unity unavailable to iOS users until Apple revoked the ban. Programming languages themselves remained a banned category until the release of Swift Playgrounds in September 2016.
That's not Apple's only category ban of note. One example was strategy games having the Confederate States of America as a faction. It took until June 2019 for Apple to even let developers give their users a free trial, which Apple had banned until then. Another was (and to my knowledge still is) Wi-Fi mapping tools because Apple refuses to provide programs with a way to prompt users to opt into the necessary functionality.