I guess that this is a bet that super heavy-weight (hopefully webasm-based!) web applications will become widespread. Think Adobe Premiere Elements in the browser.

If the browser becomes the main platform that people use to ship applications, this could be useful. And why would the browser be the main platform for apps? To bypass the app store fees, to be multiplatform, to be always up to date.

One final advantage to running the browser remotely is that you don't have to deal with a certain browser engine that is lagging behind the others.