The only question I have about offsite .pkgmeta-ing is: why are they still included in nolib packages : by design or because of some restriction ? And in both cases, is there any chance that this will change in the future ?
Ideally it would not be included and the Curse Client would be able to pull the library from the off-site source specified in the .pkgmeta as a disembedded library, but since that functionality doesn't exist (and because it probably wouldn't be very considerate of nor easy for the CC to pull things from other people's sites every time someone downloads the addon anyways), off-site embedded libs need to be included in nolib distributions for practical reasons.
Some people seem to fail to get the point that since its not located on WowAce or CurseForge, even if you embed it via the .pkgmeta file as an external it still is always in the zips, both the normal and the nolib. Thus the argument against putting it in the .pkgmeta because there is no standalone version is moot.
It's about educating authors and getting them to do things correctly instead of saying, "meh... it doesn't matter - this won't work anyway"