I'll try to respond to some of your comments, but I'll admit I'm always somewhat confused by rant posts. I never really understood PPAs, that seems like an Ubuntu thing that was not ever suggested to use in debian. If you want to stay on bleeding edge for packages, the suggestion would be to use debian sid.

I'm not sure what you mean 30 GB of memory. How is that related? And how would merging the -dev packages into the library packages solve it? IMO there are problems with the Debian approach but I wouldn't say that's one of them -- a worse problem to me is that things like cross-compiling/multi-arch mostly requires chrooting which is a lot less convenient than the approach used by something like Nix.