What people forget is Apple's fee is a lot less than what it used to cost to bring a product to market, and essentially made the barriers to entry so small that a lot of small developers can be successful; and they only pay 15%.
Before App Stores, a developer was lucky to get 30% of a sale, and had to upfront many of the costs that Apple et.al. eliminated, and they didn't have to find a distributor that would even take on their software.
This is just pro-Apple propaganda, in the early 2000s most indie Mac apps were not distributed in the way you describe but rather were over the internet already.
Only larger sellers that actually wanted to sell boxed software were hit by these distribution fees. The App Store did not meaningfully lower the cost of distribution because by the time it came along much of software distribution was already moving to the internet with very very minimal distribution costs.
It also forgets that one of the reasons why Nokia Symbian lost was because the tools were paid and there was no cohesion around the dev story. Symbian also required devs to manage their own code signing which was also another annual fee.
Apple used "free" tooling and signing as a way of competing early on. Ease of use of the developer platform is IMO a larger part of Apple's early app store success than their monetization scheme.
Today the App Store provides no discovery benefits unless you mange to catch the notice of one of the App Store reviewers and get featured on the editorial page. There are thousands of indie apps that never get noticed and have only a handful of downloads.
There are things about app stores in general and Apple's in particular that should change, but a 30% cut for developers making over a million US is not unreasonable, and they cover much of the costs of all the free apps as well.
As for lower fees lowering prices, which is the real benefit to consumers, that didn't happen when Apple reduced the fees for small developers, so who's being greedy?
When developers have a choice (the Mac) The App Store is often not the preferred distribution mechanism. On iOS bigger devs have managed to game the system so that they never pay this 30% fee, MS, Amazon, Adobe, none of them really bother with Apple's fee as they have their own systems for subscribing and signing up that avoid paying Apple any money (though last I checked MS still at least gave users the option to use Apple's payment system).
On the Mac many devs would rather you buy the product directly from them and download it from their website than go through Apple's store. This suggests that Apple's fee structure and store restrictions aren't to the benefit of developers anymore but is to the benefit of Apple.
App Stores are to the benefit of the consumer in many ways but if Apple can't incentivize developers on the Mac to use its store it suggests that Apple have prioritized their own needs over the needs of the consumer. If they truly valued consumers as highly as they claim they would try and reduce the barriers that keep devs off the Store. Sure a few indie devs put their app in the store but even those have started to leave due to the restrictions making it hard to build the kind of innovative apps users expect.