While that works for Chernobyl, if you have a real world systems you might want somewhat more practical access.
Of course exposing industrial hardware directly on the internet is the other extreme, and you get what you're asking for.
Do something in between, if you even just apply normal network security you'll be ahead of the pack.
Problem is, a lot of these systems are not built by IT people. While they have a lot of quite admirable skills, it's just not their primary job, and thus they tend to lack the necessary paranoia at times.
The problem is there's no good way to actually enforce this. Every organization has their own idea of what is "good enough". The NSA has some pretty good advice[0]. But as far as I know there's no written-in-stone engineering standard organizations have to meet, just "best practices". If the building inspector finds fault with the construction of your facility, it gets evacuated and shut down until the defect is remedied. There's no inspector for your network security. That's the problem.
[0] https://media.defense.gov/2022/Jun/15/2003018261/-1/-1/0/CTR...