I've seen similar things in this decade. Lots of stuff still running where the last change in design was 20+ years ago, the current team knows how to keep the lights on and replace parts, and calls a vendor if something goes end of life and asks for a replacement part, then configures it the same way that the older one was.

It's quite reliable, and does not require paying for a team of people who wants to try new things. Once this happens for a long while there's no one in the building left who's going to advocate for change, since the only thing all that fancy new technology brings is the next 5 years of nobody getting a bonus because operational metrics weren't being met anymore.

You have to try really hard to convince these people that the thing that they have seen on a daily basis to work just fine for the past twenty years is no longer good enough, because all their evidence says that it is. And you should also listen to them much more than people who just want to use the latest thing typically do, because they do have the decades of experience seeing how things actually fail.