silva
I suspect you have worked on a few of them, they will have been applied in accordance with manufacturers specs, and installed and housed originally to that spec, it't just that the standard of care is rarely kept up.
I mean their internal designs, not the machine designs, though they are rarely an issue for the drive due to the applications engineering support that was given globally to the machine builders.
Once they fail, it's just a drive swap anyway, and send it off for repair.
So no real biggie.
If their "home" is kept up to scratch they do have a very long service live, I've seen them having lived in the field for 20 years without failure.