Reading the part about using foam to make these drives quieter, and the link to the author's other article about putting drives on foam, makes me write this obligatory warning: hard drives do not like non-rigid mounting. Yes, the servo can usually still position the heads on the right track (since it's a servo), but power dissipation will be higher, performance will be lower, and you may get more errors with a non-rigid mount. Around 20 years ago it was a short-lived fad in the silent-PC community to suspend drives on rubber bands, and many of those who did that experienced unusually short drive lifetimes and very high seek error rates. Elasticity is the worst, since it causes the actuator arm to oscillate. The ideal mount is as rigid as possible.
As someone with a bit of experience on this topic:
HDDs doesn't like micromovements. If you put it on a pink foam mat (both a computer and yoga ones) it wouldn't matter. If you 'rigid mount' it but your screws would came lose then your HDD wouldn't like it because it wo&ld result in microvibrations from the self induced oscillations.
Rubber washers are good because they eat those microvibrations. The hard foam which is talked about in the linked article is not good because it is bad from the all aspects - too hard to eat up microvibrations, too soft to be a rigid mount.
The worst thing you can do is to rigid mount an HDD to a case which is a subject to a constant vibration load eg from a heavy duty fan or some engine.
I've been mounting my 3.5" hard drives on those "fad" rubber band 5.25" drive bay adapters for decades and have not noticed any increased failure rate at all. Sure, seek time may be worse, but the reduced noise has been worth it for me.
The problem isn't just slower seeks; it's when vibration causes the head to go off-track and write data where it shouldn't, faster than the servo can correct. Track pitch in modern hard drives is only a few dozen nanometers.
I’ve worked at a scale that is statistically relevant. Tens of thousands of drives under my control. I’ve seen a ton of different failure modes. Some of our anecdotes are actually useful. The problem with book and lab theory is that sometimes the theoretical problems don’t manifest (SSD wear out for example) and sometimes the minor seeming things turn out to matter a lot.
