I have it on an HTC One M8 on T-Mobile. Maybe he has a manufacturer that doesn't like to update (coughSamsungcough) or a lazy carrier. But non-Nexus devices definitely get updates somewhat regularly now. Most manufacturer/carrier combos definitely got their act together compared to a few years ago.
I'm on the Sony Z3. Apparently some varities of the Z3 in some countries on some networks are getting marshmallow at the moment. But not mine, yet at least. It's not just Samsung who take ages updating, or who ignore the deal they're supposed to have with Google to provide major updates released within 18 months of the release of a device.
Google didn't sell you your phone, why were you asking Google for a new OS for your phone? Sony got Marshmallow from Google, Sony is refusing to give it to you.
He, some versions of the Z3 are getting the N(!)[1]. I'd say it's probable that it's your carriers fault, the Marshmallow updates for the Z3 have been out for a while.
