Good question.
Answers to the questions
All hard disks can be used in a computer as long as the connectors are of the right type. There's never any additional software needed to connect to a hard drive. SATA RAID drivers are for the motherboard, not the hard disk.
NTFS formatted is bogus too, because that would mean the hard drive is prepartitioned. This can be the case for external hard drives, but even if so, it can always be repartitioned/formatted, and most OS's will report so and help you format the drive if necessary.
The third bullet is pointless too. A hard drive is meant to be used in a computer, and as such, as long as the OS supports hard drives, they can be used. The only OS I can think of that might not support hard drives are MS-DOS 1.0, from the era when floppy drives were the only storage medium. So yes, even though Linux is not mentioned, they can be used.
But why?
Now that I've mentioned that this information is redundant, there are a few reasons why this information is listed.
The biggest reason is simply demand. You and I know a lot about computers, but there are people who don't know anything. They hear that their Mac is not a PC and when they buy a hard disk, they wonder if it will work with their Mac too, so they raise the question. Whenever there's doubt, people tend to overstate the obvious, so information like this is added because it appears to be one of the most frequently asked questions from the novice user.
Another reason is that a product sells better when it has many points listed as features. If you want to buy an MP3 player, and you see 2 nearly identical products, and one lists that it can play MP3 files whereas the other doesn't list that it can, you will buy the first one even though it is plain obvious that the other one will too. Its not listed so maybe it doesn't play MP3 files at all?
There are probably more reasons why this is stated, but I can't think of them right now.
1Actually, back then, it was PC-DOS. MS-DOS only came about as Microsoft started selling the same code to companies working to clone the IBM PC. And yes, Microsoft's DOS 1.x only supported floppies; 1.1 added support for 180 KB (yes, kilobyte) floppies, and 2.0 added support for hard disks and such advanced features as gasp directories. Before 5.0, you couldn't get DOS directly from Microsoft as a consumer product, so you'd see names like Compaq DOS, Amstrad DOS, Ericsson DOS and whatever else as manufacturers took Microsoft's OEM kit and adapted it to their particular hardware. – a CVn – 2016-10-24T15:18:27.923
@MichaelKjörling Good point. The only reason I used MS-DOS, because everyone knows it, and I wanted to clear the confusion between Windows-Dos aka command prompt, even though technically it is MS-Dos 7.0 or higher. – LPChip – 2016-10-24T15:45:20.477
Except in cases where it isn't, such as anything deriving from the Windows NT product line. MS-DOS died with Windows ME. – a CVn – 2016-10-24T15:53:39.830