Let's face it, not everyone's first thought when they have a technical problem is to Google it. You might be the designated 'tech person' for your family or friends, making sure granny doesn't get malware on her dusty Windows XP desktop. Some people need an actual person to help them, and that's completely okay - that's where Google Support Services comes in.
One of the Pixel's exclusive features is 24/7 support straight from the Settings app, which even allows support agents to control your device (if you allow them) if needed. Now Google has published the Google Support Services application to the Play Store, to allow updates without new system updates.
By accident, Nexus owners with the Android 7.1 Developer Preview were actually able to receive support as well until Google disabled it. Now the Support tab in settings just has links to Google's online help.
Despite only working on Pixel devices, right now Google Support Services can seemingly be installed on any Lollipop device. I'm sure this is a bug that will be fixed, but it's interesting nonetheless.