I had the exact same thought! One guy could maintain their OS. No forced compiler flags, internal binhost, everything else same as what they had.

There's even a thing called GRS (Gentoo Reference System) - a predefined Gentoo configuration that predictibly generates identical Gentoo installations. It's probably a chore to set up (that is, more than an ordinary Gentoo), but I expect it would make it very easy to maintain hundreds of installations based on that GRS.