Just off the top of my head, Ross Scott on youtube (AccursedFarms) has plenty of videos on the subject. A few of them are tucked away in reviews but he now has a dedicated "dead game news" series.

These may not be games you'd want to play but the important message is that it's concerning that the biggest publishers (Ubisoft, EA etc.) can release stuff that will randomly die at some point in the future for no good reason and that they won't even release a patch or server software so you can play the product you paid them for.

You're talking about games that were online-only where the servers have been shutdown. This is not at all what the comment I'm responding to is about, which is games that rely on a DRM that connects to the internet to validate your installation, meaning that even full solo, fully offline games would stop working.

There's lots of games where even the single player campaign needs servers to use.

Remember Games for Windows Live? Pretty sure the original version of GTA4 is no longer playable without cracking it due to GFWL being shut down.

Microsoft released a version of gfwl that uses Xbox servers.

Only online features are disabled.

Here is a (probably not exhaustive) list:

https://www.pcgamingwiki.com/wiki/List_of_games_using_Always...

This is an incredibly misleading link. Most of those are online-only games that have been shutdown (or the multiplayer part of the game has been), it's not at all the same as having a DRM that needs to reach a server for a purely solo experience.

Sure, but there are also single-player games on the list. You asked for a source that such a thing happens. The link proves that it does.

Again, it doesn't prove anything.

If you see the top of the table it says "Specifically games no longer listed as being available for sale through any means.".

It doesn't mean you can't play the game if you already acquired it...

I have Steam games that aren't sold anywhere anymore but I can still install and play them just fine.

From memory: Assassin's Creed 2, Hitman 2,3, etc.

AC2 only the multiplayer is missing. Game itself works.