Still have this one sitting on my desk:
They are passive devices, no electronics in it. CF cards were designed to interface directly to the PC Card Slot, the adapter only remaps the pins & form factor.
Do you remember the CF Micro Drive? Back in the day, if you wanted large capacity, that was the way.
I still have an 10 year old Kodak 2MP digcam that uses CF.
Within the next 10 years, it will all be flash, hard drives will be gone.