I think it only limits "freedom" in that it only makes sense on Debian-based operating systems. Whereas I can and do run npm on tons of different Linux distribu

I think it only limits "freedom" in that it only makes sense on Debian-based operating systems. Whereas I can and do run npm on tons of different Linux distributions, MacOS, and (theoretically) Windows. You can do things with deb packages on other Linux distributions kinda-sorta using various programs and scripts, but it's not painless. And Mac and Windows are right out. The same applies generally as to why there are usually two types of dependency managers. One for binary packages and binary shared libraries (even though these often include source code for C & C++ stuff), and one for specific language development environments. See also Rust, Dart, Python, Ruby, Go, Lua, etc., etc. All those languages have their own package managers.