Gentoo user since late 2002 here.

I agree that the state of stable is quite poor of late. I surmised there're a variety of reasons behind this: I'd say the explosive growth of Arch Linux is part of this, personally I've seen much of the community move there. If you look at the state of Arch Linux's community and documentation, you'll see strong parallels with Gentoo a couple years back. Another is Docker leading many people to want a homogenous environemnt using Docker and Debian, Centos or Ubuntu.

That said, I've no plan to move away from Gentoo and found that sentiment mirrored amongst a substantial core of Gentoo "power users" for the lack of a better description.

Why?

   Ebuilds, when you want something "just so", you roll 'em "just so"
   Use flags, ties into the above
   OpenRC.ymmv, but systemd is an anathema, there's been much discussion on the topic so I'll leave that out
   hardened-sources
   Given privacy and concerns I will never trust a binary only system any more than I trust the organistion behind it. With gentoo I need never trust a binary blob should I choose not to

It's worth pointing out that this current state of affairs is relative to the pinacle a few years ago, and that even in its current state the Gentoo community is way more responsive than many comparable communities. I had Firefox 32 (~amd64) within minutes of release, no such luck on my Macbook.

I'd still never recommend Gentoo to new Linux users that lack the curiosity to find out precisely how all facets of their system fit together. If you want a system that "just works", Gentoo isn't it. If customisation uber alles is your battle cry, then you'll find no parrallel.