It's easier to maintain a very fine-level of control, but only if users are prepared to invest the time and effort to keep themselves up to date on the software that makes up their system. Sure, that is probably assumed to some degree as part of being a power user, however alternatives like Arch and nixOS are capable of providing similar levels of configuration with a little more ease, at least in certain places.

> but once you've got it setup it's easier to maintain.

In general, this is not the case compared to more out-of-the-box distros like Debian, where upgrading is simply a matter of "apt update && apt upgrade".

Nah I totally disagree. This is true of Arch, but Gentoo makes it incredibly easy to screw up your system. You never really truly break things, of course, not in a way you can't fix. But if you start adding USE flags all over the place it's pretty easy to get to the point that you can't update anymore because of endless blockers and other weird stuff.