Because then it doesn't matter what you're running locally, as long as you've got a supported browser (Chrome, I'm guessing). It means it doesn't have to make a difference if you have a Window 10 desktop or a MacBook Air or a Chromebook. Go to the web page and look at this CAD.
It is fine 'cause it uses the browser you're already using anyway instead of importing a new one for each and every application. Run the backend on a server somewhere and you can get to your application anywhere you can reach that server which - using a self-hosted VPN - can be anywhere you have internet access.
