I have this problem that I constantly go and start coding because I got an idea while some friends wanted to play something. I mostly keep myself under control with this but I cant play too much sessions when there arent enough people to encourage me in this state. But its not happening everyday.

I've been streaming D4 through steam, so that tracks my play time. Unfortunately I don't think there's a way to check through Bnet.

this site exists and has some stats available like play time

https://d4armory.io/

I don't believe there is a way to currently view that info. Hopefully Blizzard adds it at some point. An API would be nice as well.