“Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.” — https://en.wikipedia.org/wiki/Jamie_Zawinski#Zawinski's_Law

That explains why Google puts messaging in everything.

    Did you get the Google Doc's message I sent you?
    Oh yeah, I replied in Google Pay.

I thought this law was just a joke, but after Manny years of development, I'm finding out it's very real.

It's also increasingly painful to make happen in today's email ecosystem.