Hm. How it's different from home-manager?

I've never really understood how version pinning is meant to work with devenv.sh or Nix more generally. If I whack a .tool-versions file in my repo, everyone who works on it can use install the exact same versions of the relevant tools using asdf. That's low tech and imperfect (and certainly not a replacement for all of Nix's features), but it works as far as it goes. None of the examples on the devenv.sh page demonstrate pinning of tools/packages to specific versions.

As best I can tell, Nix enthusiasts think that this is an XY problem and that I shouldn't want to pin individual tools/packages to arbitrary versions. But the thing is that I am a rude barbarian who very much does want to do this, however philosophically misguided it might be.

Can you help me understand why devenv is needed instead of a shell like this/what is gained?

    { pkgs }:
    
    pkgs.mkShell {
      nativeBuildInputs = with pkgs; [
        # build tools
        cmake
        ninja
        gnumake
        pkg-config
      ];
    
      buildInputs = with pkgs; [
        # java
        jdk8
    
        # compilers
        gcc
        clang
        llvmPackages.libcxx
    
        # libraries
        capstone
        icu
        openssl_3
        libusb1
        libftdi
        zlib
    
        # scripting
        (python3.withPackages (ps: with ps; [
          requests
          pyelftools
        ]))
      ];
    
      # capstone headers are in include/capstone/ but blutter expects include/
      shellHook = ''
        export CPATH="${pkgs.capstone}/include/capstone:$CPATH"
        export CPLUS_INCLUDE_PATH="${pkgs.capstone}/include/capstone:$CPLUS_INCLUDE_PATH"
      '';
    }

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