To collect as much customer data as possible, to (hopefully) anonymize it and bundle it to sell them to data brokers and extract more money from their customer base...

All of it with their "consent" (you installed the app and likely accepted their ToS/PIvacy Policy), under the pretense of providing them a service like counting the time/frequency of your interaction with the product or reminding you to use it (something you would already do anyways, maybe less accurately, if you are a functioning adult).