It's the ecosystem. Without an ecosystem there will be less adoption and consequently less investment in the OS. Where I stay, so many services offered exclusively through Android/iOS apps with no alternative. Even government services are slowly excluding the web and becoming app only. There is an implicit expectation from everyone that one will have either an Android/iOS device and this only becomes stronger with time.

I don't know how many people realize but what can result from this can be very dystopian and is scary. But the best possible outcome from this I hope is that some day a wise government realizes how much of daily life is dependent on two corporations and passes regulations to standardize app runtimes. You should be able to publish applications that can run on any OS. Only then we'll see competition in the OS market.

Interestingly, we are, and have been, at a point were you can publish applications that run on any OS for a while, with PWAs.

There are very few software examples, that couldn't be distributed as PWAs, including secure things like banking, etc. With WASM in the mix as well, theoretically the sky should be the limit.

Even more interestingly it hasn't happened - mainly because Apple and Google haven't got behind PWAs for obvious reasons, so the app ecosystem just doesn't exist. It's hard to see how this will changes, when mobile operating systems are dominated by two players, with very obvious incentives to make things worse for consumers but better for themselves, by grabbing as much control of the apps on their system as possible.