That's the cost of supporting code that is constantly being updated, you need to start freezing versions and backporting fixes. Also, I'm not sure what command line tools you're referring to as "differing over time". Kernel version freezing is mainly fear of new code (or out-of-tree vendor patchsets that depend very strongly on the kernel ABI which changes every few months -- but that's not user visible). Sure, if your system never changes anything you don't need to worry about software versions. But there are many other problems with that.