Spin down isn't as problematic today. It really depends on your setup and usage.
If the stuff you access often can be cashed to SSDs you rarely access it.
Depending on your file system and operating system only drives that are in use can be spun up. If you have multiple drive arrays with media some of it won't be accessed as often.
In an enterprise setting it generally doesn't make sense. For a home environment disks you generally don't access the data that often. Automatic downloads and seeding change that.
It's probably decades old anecdata from people who re commissioned old drives that were on the shelf for many years. The theory is that the grease on the spindle dries up and seizes up the platters.
If the stuff you access often can be cashed to SSDs you rarely access it. Depending on your file system and operating system only drives that are in use can be spun up. If you have multiple drive arrays with media some of it won't be accessed as often.
In an enterprise setting it generally doesn't make sense. For a home environment disks you generally don't access the data that often. Automatic downloads and seeding change that.