Because the web browser did what systems developers have failed at for at least 60 years: creating a platform that can host an application that just works on many different devices.
There is no serious comparison to the performance and richness offered by native applications. Famously (and wisely), Apple quickly reversed their decision on web apps for iOS devices.
That's long gone. Long long gone actually. Now browser is such a huge and capable platform that there's nothing comparable available anywhere.
Even XBox controller's drivers come baked into browser. Just check the number of APIs on MDN.
As for performance, that's already not anywhere into discussion. Check Google Docs. Everything single thing you are on screen is drawn using Canvas and it works just.... everywhere.
They make money getting their cut of ios app payments. They wouldn't be able to do that for web apps. So they've done their best slowing down adoption of pwa's to keep that revenue coming.
Because the web browser did what systems developers have failed at for at least 60 years: creating a platform that can host an application that just works on many different devices.