A lot of this hardening is based on a fairly obsolete Unix view of the world. E.g. preventing users from seeing other users' PIDs, changing /etc/securetty, non-root X server... In real life, nowadays, a single system is likely to be running a single application, and once that's owned there's very little of the rest of the system to take over.

Owned a Web app with access to user accounts? That's enough to steal all the credit cards flowing through it, and spy/scam all the users in it. Becoming root, or peeking into other users, is usually unimportant because there's nothing special happening there.

I guess Kubernetes is the one thing that sort-of brings back these concerns, but even that has its own more modern particularities (e.g. the guide doesn't even mention cgroups).