Because we have to deal with people as they are, and not as how we want them to be.

This is for sending large assets from party A to party B, where either the parties do not have access to a shared rsync-capable server, or they do not know how to use rsync. On a deadline, you can't afford to become a CLI trainer or require special software.

A common use case would involve service bureaus and creators. Trust me when I say that there are a hell of a lot of creators out there who would never be able to manage rsync. You want to make stuff like this drop-dead simple for people. That means a service that works in-browser.