Why people are excited about this OS, I don't know :)
IMO, This is the best thing about browser as an OS. You can run untrusted apps and know that it couldn't steal your ssh keys or other things without your consent, similar to iOS and Android.
When all your data is on a server its like you dont need a sandbox any more. :)
For all practical purposes, file system sandbox features might actually be the first to become meaningless again when more and more data is stored in offline browser caches
And application delivery in enterprise environments is also much more lightweight compared to VDI solutions like Citrix so there’s another benefit in terms of sandbox and isolation
For complex software (e.g. video games) on the other hand the web is a real piece of crap: performance suck, no UDP, a certain browser is purposely a ton of useful APIs (or is straight up buggy).