I was under the assumption that:

If you are flying within continental Europe, generally you don't get stamps in your passport anymore, especially if you are European/have an EU passport.

Then I heard that you can get stamps if you ask.

So I thought if I asked and considering I don't have an EU passport, I would get one.

But I discovered that, at departures I can get one easily. But when I arrive back in Geneva they ask me where I live and since I live in Geneva (they said if you have any sort of residency permit) I can't get one!!

Do you think if I told them I don't live here they could then look it up and I'd be in trouble? I did notice they didn't scan the passports like they do at most other airports.

I don't need them for any particular reason, other than they make nice souvenirs.

It does make a nice souvenir but when you have to start adding pages it gets to be a nightmare.

It can also cause problems for you if you've traveled to one country that stamped your passport, and are going later in life to another country that hates that country, and they see the stamp.

But those are rare cases. The only notable exception would be Israel and it's neighbors. In which case Israel authorities will sometimes on request stamp a piece of paper if you wish to later travel to Syria or another unfriendly nation. Although I don't know if they still do. I have used that process before without issue.