I've heard first-hand accounts of them being used in manufacturing automation up until fairly recently, particularly in pharmaceutical manufacturing. But now a lot of that has moved to emulators running on standard x86 hardware.
You can imagine the resistance to shutting down a manufacturing line that's been running fine for decades simply because the hardware is old. A lot of expense goes into getting everything cleared with the FDA, so it's not a trivial matter to replace hardware and software.
Modern PCs cannot even drive a parallel port with the correct timing. PDP/VAX CPU, RAM, and storage are emulated, but Q-Bus and Unibus interfacing needs to be done with custom hardware.
You can imagine the resistance to shutting down a manufacturing line that's been running fine for decades simply because the hardware is old. A lot of expense goes into getting everything cleared with the FDA, so it's not a trivial matter to replace hardware and software.