Earlier quoted context omitted.
This is security (and thus stability) by obscurity basically. By being an obscure userbase, a niche. Browsers, compilers, SSL/TLS libraries, operating systems and so on doesn't have this luxury, and thus this has a knock-on effect.
I would not say that non-web software is "obscure". You probably interact with it as much as you interact with desktop/phone software -- think vehicles and home appliances. And factories that produce all the stuff you use are famous for having very old software -- I would not be surprised if a factory which makes springs for your chair still has some MS-DOS machines around. Remember, the post I am replying to says "n…
I meant obscure as in: except from a very specific persistent and advanced adversary (APTs) no one will even try to hack something like that directly. Sure, it's possible, so it's put behind a lot of firewalls, middlewares, wrappers and message queues. At least that's how one insurance company I work with uses COBOL. And if they can avoid touching it, they won't, because it's so hard/risky/expensive, and the risk of external security intrusion has been deemed low. It's abandoned as a product, as a goal, it's basically an aging power tool at this point, that will eventually give up. (Like embedded stuff.)
I know 3 years is not that long. I'm just saying that the various forces (business and security aspects) that be usually dictate fast turnaround, or at least a certain minimal level of upkeep.
Java, C++, Rust, PHP, JS, etc. all have quite a big velocity nowadays.
Python 3.5 just got EOLed.
Sure, you don't have to upgrade every last piece of python script. After all RHEL and other distros still provide some py2 support too. And if your business is not growing fast, your build system is "done", then you don't have to touch it much. But eventually it'll need some maintenance, maybe just a few touches to keep it future proof, but that again also implies that it's a niche, a custom software that does what you need it to do, that's likely not a high-profile target directly.