What Spotify is trying to do is called a roll-up. This is a well tread business tactic favored by aspiring monopolists and the strategy is simple: acquire most of the distribution in the space, then jack up the price. (In the podcast world, "distribution" equates to "listeners" and price equates to "Spotify's subscription and ad revenue.")
The harm caused to both consumers and producers by a roll-up is well-documented. The legality is questionable but US regulators have been asleep on the job for decades.
A rollup is where you merge businesses doing functionally similar things, gaining economies of scale on costs. Its most often used for geographically distributed family businesses, such as Dentists. Dentists all need a lot of back office support, marketing, and sales functions. Having a rollup with a dozen Dental offices allows you to centralize all the insurance claim handling, direct marketing and put them under a single brand you can advertise on more mass market media.
You are correct that where rollups are used in regulated industries that limit entrants such as radio, they lead to oligopolies. If you own most of the radio stations in a single city you not only get the rollup cost benefits, you can also increase your prices for advertising.
But this is a direct effect of the market limitations that would occur either way, even if owners weren't allowed to reduce costs by buying stations in the same city to combine back office and operations, they would still do it to get oligarchic pricing power. And if you try to rollup most of the Dentist offices in a single city to raise prices you can only succeed temporarily, because it's a free market and your higher prices will attract lots of new entrants.
Of course the other criticisms of rollups is they reduce diversity of offerings. In the case of radio it leads to homogenization of station playlists. Which is exactly what the BBC does in Britain, so I don't see the issue. Especially since radio is being gutted by the internet anyways.
Applications used to be distributed everywhere, but Apple tightly controlled the platform and crippled the web browser. They even prevented Flash and other runtimes so they would be the only way to get native control on the device.
Not exactly. Podcasts were openly available as downloadable, RSS-friendly MP3 files for a long time. Apple required iOS apps to be distributed through the app store. Before that, there were no iOS apps to speak of.
Web pages are the iOS equivalent to open podcasts. iOS didn't stop those from working, although it did limit support for PWAs, which arrived years after the App Store. Even then, I can use apps like Uber without the App Store: m.uber.com.
Not all companies will try to create a web experience that's 1:1 with the mobile app, but it's not something iOS prevents.
This is true, though I would argue that there is a difference between creating a new platform where you have full control and trying to hostile takeover an existing open platform. On one hand you can at least give Apple credit that they're trying to maintain some level of quality on the platform they created and expand their margins through software purchases (since the margins on hardware aren't that high or flexible), whereas Spotify isn't creating anything -- they're just trying to make a platform that already exists shittier.
The harm caused to both consumers and producers by a roll-up is well-documented. The legality is questionable but US regulators have been asleep on the job for decades.
Fortunately Americans are starting to wake up.
Matt Stoller did a piece on this last year: https://mattstoller.substack.com/p/will-spotify-ruin-podcast...