Several organisations I used to work with still have old 386/486-class machines in service. Albeit generally with IDE-to-SATA converters so they can run current-generation hard-drives. (It's odd though to see a 1Tb hard-drive where only a single 320Mbyte partition of it is actually being used!)
Two reasons why they do this:
Firstly they have a couple of decades of software written in x86 assembler to do all sorts of real-time stuff with custom-built ISA interface-cards that connect to the real-world.
Secondly, the 'downtime' to replace all the kit with modern stuff and transcribe all the programs into a modern language like C++ and then get the facility tested/recertified on the new platform would _not_ be acceptable to their lords and masters.
Alas, because of the realtime and real-world nature of the applications they can't run the x86 code in any kind of virtualisation environment like VMWare or VirtualBox either: virtualisation doesn't really cope with semaphores and interrupt-grading very well.
The predecessor of all this was based on CAMAC [
https://en.wikipedia.org/wiki/Comput...nt_and_Control ] and used DEC LSI11 controllers.