Landlords don't create the value themselves, they are an intermediary for value.

Platforms don't create the value themselves, they are also an intermediary for value.

The value app stores provide is reach, but they don't get that value without the developer's effort. The only thing they provide is the network effect, which is nothing more than a consequence of making themselves the default option for users of these phones.

For the same reason that landlords don't provide inherent value, but still capture so much of the housing market, platforms don't provide inherent value, but still capture so much of the app market.

They push out competition. If a landlord buys a house, there's one less house for someone to buy. If an app store brings in another user, there's one less user that will use other means to acquire an app.

I myself primarily use alternative means of installing apps. Direct APK downloads, or F-Droid. The only reason these exist is because the apps I use are specifically targeting a privacy-conscious user base that is likely to be using alternative means to acquire apps in the first place.

Because these platforms immediately monopolize user acquisition by bundling themselves with the OS, they directly fight any pressure to use alternative means, which makes most app developer efforts to create alternative means not worth the time.

App stores can and should be free. Without an app store, Apple and Google would have barely any market for their phones.

These platforms exist to give the hardware & OS itself value. The only reason these fees exist is because they are monopolies.