Niantic does not stop Ingress or Pokemon Go from being playable on rooted devices.

Rooting a device is the Android equivalent of jailbreaking an iPhone, a means of unlocking the operating system so you can change system level files and give apps the ability to do things that they normally would not be able to do, such as change the location of the phone in the world.

This means that anyone with half a brain, $2.99 for the Fake GPS Pro app and YouTube can figure out how to root their device and use the app to set their GPS location to any place in the world, without Ingress or Pokemon Go knowing that they've done it.

This causes major problems for those that play the games as they should be played, because the cheater that uses GPS "spoofing" can do things much easier and "win" the game without ever leaving their house. This is against the Terms of Service of the game, but in reality the only thing that Niantic can do is to remove (ban) the account that is caught spoofing... and what we see is that Niantic rarely even does that.

This is a reactive approach and has proven time and time again to be ineffective, as the person doing the GPS spoofing just creates a new account in the game and continues doing what they were doing before.

The only way to deal with this proactively is to prohibit the games from running on rooted devices.