I've worked on systems this decade that still relied on floppy disks. It's getting harder and harder for them to operate because the disks are getting rarer, as are the drives. And often the essential component is not the disk itself. There are some other computers in the system that cannot be upgraded to any more recent device, systems from the 1980s and 1990s that force them to continue using a floppy disk.

If it was just two modern computers and transferring data between them, the floppy disk would have been dropped in a heartbeat. But it's the old computers still in the critical path that are holding everything back. And those are really hard to maintain. Last year we phased out a system that was dependent on computers from the mid-1990s, getting replacement parts was practically impossible, they mostly just don't exist. You'd buy old systems off ebay and hope that they had enough working parts to scavenge, and the right working parts.

EDIT: Light editing because I had some extra words.

Systems are dynamic, not static. There are secondary consequences and forgotten/ignored opportunity costs. Sure, the existing system has proven workarounds, though labor and attention intensive. When a floppy disk fails it won't directly create disaster. But these legacy requirements do block the more cohesive and thorough introduction of additional safety mechanisms that increase redundancy and reduce the scope of possible human error - such as new sensor hardware and their automation, latency improvements, and information synthesis/notification clarity.

Here's a software analogy - required support for very old OS versions often interferes with the scope, simplicity, and security of new feature work, and even if the work is still feasible at that point it is slowed down greatly, eating up attention and time that could go towards addressing other important issues. That accumulates over time, and cumulative loss of improvements that could have otherwise been made has a real effect in unprevented disasters and wasted controller availability.

It's both time tested and at risk of ripping at the seams. Floppy disks and the mechanisms still wear. And because neither are still made, the chances of a zero population scenario happening is greater every year.

It's better to test a replacement while you still have the time, than to risk rushing something else.

The overall reliability of a system is time invariant... its either reliable, or not.

The fact that it has gone x days without an incident doesnt upgrade or downgrade its reliability. The engineering and processes are function in an equation that calculates mean time to failure. Life-critical processes have numbers placed to this... like a failure every 50 years or 100 years... or 100000 years, and you work towards solving that.

Floppy disks aren't manufactured anymore. At some point there aren't going to be any.

Fortunately the choice isn't between 1980s hardware with floppy disk requirements and rented servers in someone else's building. There are a lot of options in between those two.