Most of the drives in external devices are "green" drives which has higher seek time and/or lower RPM. The reason why these drives' price have not increased as much/as fast is because the demand is lower than the "regular" internal drives.
I did the same thing when the "crisis" happened, I bought a load of external drive and removed the hard disk from them.
It's not a gimmick, but it's also a double-edged sword. They also do fun things like spinning down on an aggressive timeout, which can lead to early SMART warnings about head load/unload cycles if you keep waking them up to write periodic log files to them. I had to "fix" this with a nasty little DOS utility on a home Linux box I built using Seagate's version of this.
... and you should avoid them at all costs for any serious application. To this day there is still confusion between host adaptors (raid controllers) and green drives, and the firmware management process (you will absolutely need to manage the firmware on these) is atrocious.
The "green" is certainly a gimmick. But the lower power usage is not. 10 Backblaze Storage Pods full of "green" drives use the same amount of power as 8 pods full of "regular" drives.
I did the same thing when the "crisis" happened, I bought a load of external drive and removed the hard disk from them.