Perhaps someone high up in Google uses it and doesn't want it killed after a couple of years? ;-)

The whole point of the service is to automate stuff so you don't have to open their webpage ever again if done properly. This doesn't bring advertising revenue in.

On top of that, this kind of interactions are usually used by power users (individuals, not business), so it wouldn't be as popular nor profitable as they need (e.g.: Google Reader was a fantastic tool but they shut it down anyway).

Are you sure ? What are you basing this on ?

I thought Zapier was mostly business, and it's been running for a while now: https://zapier.com/

This is why I like that project. User cant be disturb as this self hosting service is yours. You are the master on board :) Do what you want ; do what you need ; share or dont etc. It is a toy that renders service.

Alphabet/Google also buy things that may have a big impact on internet usage as a mechanism to deliver more ads.

Indeed, that's the goal: reliable! :)

I think there's an overlap with Google's services. With Google, I: 1. get a notification if the roads are busy on the way to work. 2. notified when bills (that I received via email) are due. 3. and more that I can think of right now.

That's just with the Google (formerly Now?) app. With Allo and other apps Google's services are going to improve without you doing ANY ifttt-like rules.