Significant chunks of this page is really just about the steam input api.
Topic on Controller talk:Steam Controller
Like the key points: "Adds full controller support to virtually any game because of Steam Input integration with high customization and being able to use XInput, keyboard and mouse inputs."
"Can sync configurations across computers by Steam account."
These are functions of steam, nothing to do with the controller.
The Steam Controller and Steam Input is basically two sides of one coin -- Steam Input was even known as the "Steam Controller Configuration" and "Steam Controller API" initially before Valve extended support to other controllers as well.
As a result, I don't think it's weird that the page features a lot of information that is ultimately related to or a consequence of Steam Input, since that's the way the controller was designed to be used.