I've seen some defenses of Apple's now-modified-enforcement of App Store guidelines that go a little something like this:
If you think apps should be able to freeload on Apple's App Store distribution, but then not give Apple a cut of their revenue, then you must also think that it would be perfectly fair for a merchant to set up a bodega in their local Walmart and sell their wares to Walmart customers without giving Walmart a cut of the revenue.
This argument may work as a quick mental exercise, and it may win you a few retweets on Twitter for this single argument, but I don't think this is a good comparison.
First, big box retailers and an app stores are different things. There are many differences between Walmart and the App Store, so I don't think it's wise to suggest app developers need to follow the same rules as merchants selling at Walmart.
Second, if we follow that merchants taking payments for products downloaded from the App Store is like setting up a bodega in Walmart and not giving Walmart a cut, then is the suggestion that services that let you subscribe/pay in the App Store or outside of it (Netflix, Spotify, Disney+, Hulu, HBO, and basically every single SASS out there) should be forced to not let people use the App Store apps unless they are also paying through the App Store? After all, the monthly fee I pay to Netflix through Netflix directly means Apple isn't getting a penny.
Third, if I'm a merchant selling socks and I don't want to deal with Walmart's rules, I can choose to sell at Target, shoe stores, or just go straight to the consumer. Sure, being at Walmart has benefits, but if I choose not to go that route, I still have options. If you can't be on the App Store, you may as well not exist on iOS, which is not the same thing.
As I'll reitterate every time I talk about this, I don't think that Apple is legally required to allow everything on their store. I think they have the right to set rules and enforce them, and even though they're huge, I don't think they should be considered a monopoly. I have this position because I think it's better for consumers, better for developers, and frankly, consistent with how many other apps on the App Store already work.