I think your comment reflects well the mindset difference between programmers working for startups and the rest of the world. When you're working on a system that's supposed to last for decades, you think in a completely different way.
Some of the worst systems I've seen were those designed to "last for decades".
But that's also not the same as "to last decades". A lot of the old space code was used and dismissed after a few years / missions.
The key difference is not "future-proofing" but "proofing" in general: the code had to be absolutely robust.
I.e. basically everything non-web/non-mobile has a higher lifetime.