TLDR the app isn't the problem, people are the problem. Pokemon GO is demonstrative, not exclusive, marking high enough sample data to show that humans are not capable of doing many things at once.
The app has multiple mechanisms to keep people “engaged”. It absolutely bears some responsibility here.
People simply cannot not look at their phone while they're driving. We've had ample time to learn this lesson and do something about it. We haven't done anything about it except pass ineffectual phone-use laws and some very ineffectual software nags. I suppose there's a lot of money invested in people using their phones while riding or driving.
Consequently, I know a lot of people who have been seriously injured or killed.