I agree that Gentoo has its own set of issues when concerning portage ("hey I told it to do an upgrade but now I have these errors preventing such and such ebuild from running"), and that's really Q&A on Gentoo's devs to address, but do not say Portage is exactly the wrong solution. Portage is a very excellent solution, and while I don't think it is the greatest end user solution (as people who want to use packages are not interested in the notion of compiling), I do think that it could be used to generate channels for binary package building of libraries and apps to get the features (as mentioned earlier in this thread) that users want so that users can download the apps and libs tailored to their needs. Yes there are issues where "ebuild such and such is blocking such and such" in Gentoo, but I guess the same things exist within alot of package management. What Portage does do nicely is have the notion of "slots" allowing libraries and apps to live side by side. I note your reference of having to search forums for help in Gentoo, but I think your bias has blinded your total reason because if any user here states he or she never has to use forums/help for his or her operating system of choice would lead me to believe he or she is lying.
I think that Gentoo would be a good idea for all distros to use as the LSB as the way development should go... a development tool so to speak. But then the idea behind all of these operating systems we are listing is that we have choice in using what we want. When facing new users, I usually point them in the way of Ubuntu, as I want them to have a starting good user experience. People that have specific development needs, I point them in the way of Gentoo.
Getting back to the point, if Nix isn't your cup of tea, then simply don't use it. I certainly give it credit for doing what the authors attempt to accomplish, and perhaps it might have a good use in environments where different development groups exist and need different versions of libraries. I'm not really a fan of this, but this is simply the reality of what it is. Anyway, I'm going to investigate it and see if it can fill a need that certain users I support use.
Oh, and one more thing: while I recognize your life has become easier using Ubuntu, my life would be a rotting chaotic pit of hell if I had to use that on a daily basis for the kind of work I do, and it would be extremely confining. I think Ubuntu is a fantastic operating system as it his brought ease of use to numerous users who do not have alot of demands out of their operating system other than being a platform to launch their apps. However, for tweakers and power users, it just isn't the flexible animal that Gentoo is (and you are certainly entitled to disagree with me here as we are simply arguing chocolate is better than vanilla (and vice versa)), but noting that an anonymous poster tried saying Gentoo (and really Portage) solves all problems rather than discuss it (and is the real culprit in this thread), I figured I would straighten his and your nonsense out.