Obvious

This seems to me to be a clear case of the Law of Unintended Consequences.

Modern laptops (thanks largely to ever-increasing hardware demands from Redmond) have plenty of RAM. They also have hard disks which go into a power-saving mode (with the heads parked and the motor off) after spending some predetermined (and theoretically adjustable, but in practice almost nobody bothers to) amount of time idle.

Linux by default uses a highly-aggressive disk-caching policy: basically, never, ever write anything to disk unless (1) the machine is about to be turned off or (2) there is no RAM left to cache it. Entire temporary files can be -- and often are -- created, read and deleted without ever going near oxide. (That, incidentally, is why some software runs blisteringly fast on Linux, but crawls on other OSes with different caching policies.) Aggressive caching + much RAM = fewer writes to disk.

Now, when you combine a hard disk drive that automatically goes into power-saving mode with an operating system pretty much designed to leave disks standing idle, what should you expect to get?

My guess is that the reason why this only seems to affect Linux is that Windows feels the need to access the disk just often enough for the drive never to go into power-save.

One final thing: When starting from rest, a HDD motor draws several amperes for a brief instant, as it has to accelerate the disc platter suddenly from stationary to several thousand RPM -- but once it's running, the current drops dramatically as it only needs to overcome friction in the spindle bearings. It's entirely possible, by injudicious settings, to end up wasting more power on standing starts than you saved by stopping in the first place.