The value of the browser sandbox is often dismissed but it's doing a great job at allowing people to run untrusted code from the web without much thought behind it. I also strongly believe users are much more willing to try websites than download entire app anyways just to see if it's any good.
Also IMH developer perspective HTML+JS+CSS is surprisingly a not so bad UI toolkit, and React makes the development experience even better.
I will always bet on standards and, at least for now, modern web is the standard that I can trust.