The latter. Old versions of libraries aren't maintained and you're on your own to compile effectively from scratch an entire distro's worth of libraries. Ironic

The latter. Old versions of libraries aren't maintained and you're on your own to compile effectively from scratch an entire distro's worth of libraries. Ironically, it should be easier to have as strong backwards compatibility on Linux as Windows, since all .so files are versioned and almost never break the API within the same major version, so you're spared the DLL hell of a program linking with blah.dll expecting it to be version 1, but you have version 7 installed. On Linux the program would link with libblah.so.1, not the libblah.so.7 you have installed.