[gaius]

f you record that you've done your analysis with Python 3.6.3 and Numpy 1.14.2, and it later breaks on some newer version, it's relatively easy to get the same versions you were using

Better record which compiler you used too, and what flags, and every version of every library and everything else. It’s not as simple as you make out and it’s far from guaranteed that all those packages will still be available or compile on your OS.

Commercial software vendors are usually not keen on you downloading and running a version of their product which was superseded four years ago.

I guess you must not deal with vendors much because generally they are fine with this. It’s part of the support agreement usually, just another service. Getting an “obsolete” version for whatever reason has never been a problem for me.

By “anyone with a computer” you mean “anyone who can exactly reproduce my configuration which I don’t even know myself for certain”