There are a few issues with any sort of behavior change program that live solely on your phone:
1) The process to get into an app these days is surprisingly tedious - for example: touch ID, then again if it didn't recognize, get out of Facebook to the home screen, swipe three pages, then you can tap in. Each step along the way decreases the likelihood of you using the app, let alone the process of inputting your data into the app. (Compare all that to a single push of MOTI's button!)
2) The phone is incredibly distracting. When you look at it, you think of social media, emails, texts - not that running habit you're trying to form. Your phone is not an environmental cue, and worse, you're far more likely to get sucked into social media the moment you turn it on.
3) Push notifications are not very effective triggers. They happen at a single moment in time, and if that moment is not immediately actionable for your habit, they are easily swiped away. Plus, we get so many notifications these days, it's hard to stand out above the noise.
4) Studies have shown that even if you show a cute, 2D representation of a robot or being on your phone, you engage far more with an actual 3D one. It's much harder to build an emotional relationship with an avatar than it is with a being that physically lives in your environment. And it's this relationship that drives deeper accountability for your habit.