>1. One build runs everywhere, Windows, Linux, Mac, Chromebook (used a lot in schools), Android, iOS, I even have someone running it on an XBox web browser.
This also exists outside of web development (e.g. Qt)
>2. No download and install
The client must download the source code, same as any other platform. The installation part occurs when the user had to first install a web browser before being able to use your software. Outside of a monstrous application, installation is almost instantaneous these days.
>3. Everyone runs the latest version.
Nothing new here. For instance web browsers: They download in the background and silently install upon next restart. Also, running the latest version isn't necessarily an advantage, especially if it wasn't the end user who installed that latest version or otherwise has no control over whether it gets installed or when.
>4. Easy update scheme: I update the website, and everyone gets the latest version.
This might be the only advantage. Though, if such deployment is a requirement, setting up the necessary servers to facilitate the communication with the client isn't nearly as difficult or complex as it was even 5 years ago.
>5. Not giving away % of revenue to platform owners.
Unless you're talking about an iPhone app, then this isn't a requirement.