Your condescension is annoying. Have you actually read the Gentoo handbook
I decided to install Gentoo two years ago, after using Fedora for quite some time and Ubuntu before that. (I have had no formal Linux/sysadmin training, and my degree is in aero engineering- not comp sci.) In the course of that first Gentoo install, so much about how a modern Linux system functions made sense to me that didn't before. Of course there's nothing stopping me from learning all that with another distro- but the Gentoo install showed me how it all (grub, parted, lvm, filesystems, kernel config, manual network config, syslog, X, kde, mysql, iptables, apache, etc, etc) fits together to achieve the goal of a usable system.
Once I was introduced to that framework, I could begin to make that crucial step when I stopped searching forums for the right commands to paste into xterm, and instead sought an understanding by reading official documentation and manpages.
To more directly answer your questions: yes, of course I could never go beyond `emerge some_package` and not reap any of the benefits of using a source-based distro (aside from walls of gcc output text that you think I wear as a badge of pride). But since the above framework was cemented in my head, the door to tinkering was placed within easy reach; this is true whether it be as simple as manually configuring some sysadmin-type function like apcupsd, or as complicated as editing kde 3.5 source code in a local overlay to achieve some crazy idea of usability that popped in my head.
Basically, don't knock it till you try it. Learning about what makes Linux tick from a textbook or some presentation is far inferior IMO to struggling with it on your own.
And definitely please don't berate those of us who are simply enthusiastic about teaching ourselves about random Linux nonsense and don't care about your distro wars or whatever.