Apple hasn’t sold a Macintosh for around two decades.
In that time Apple has been selling Macs – iMacs, eMacs, MacBooks, Mac Minis, and more. The URL for Apple’s online store is http://apple.com/mac, and not http://apple.com/macintosh. The latter shows the error message: “The page you’re looking for can’t be found.”
As far as I can tell from a cursory inspection of Apple.com in the Wayback Machine, it appears Macintosh was finally dropped completely around 2001, although lingered for a few years afterwards when describing Apple’s server lineup, such as Macintosh Manager. Wikipedia says Macintosh was dropped in 1998, shortly after Steve Jobs’ return.
Put simply, since the introduction if the first iMac, the term Macintosh has become verboten. Dropping the term served as a necessary break from the past.
Apple produces a style guide to tell people how to correctly refer to Apple stuff when writing and, whilst acknowledging Macintosh as a trademark, the entry for Macintosh reads:
Macintosh See Mac.
And when we look-up Mac, we find:
Mac Use Mac to describe Mac computers and related products.
a Mac computer; the Mac; a Mac; your Mac; Mac users; the Mac platform; Mac software; Mac-compatible products; your Mac, iPad, iPhone, and iPod touch; a Mac or iOS device; Mac computers and iOS devices; for Mac and iOS; your Mac or PC; Mac computers and PCs; for Mac and PC; for Mac and Windows
While we’re on the subject, it’s not “MAC” either. I have no idea why people want to capitalize the letters like this but it’s extremely common online, even amongst people who have been Mac users for decades. Perhaps it’s because we capitalize “PC”?
To complicate matters MAC is actually a computing term, but it’s not specific to Apple hardware. MAC means media access control and refers to the unique address an item of networking hardware has. All computing devices capable of connecting to a network have a MAC.
UPDATE: In the comments below Jai points out an interesting anomaly – by default the hard disk in an OS X installation is named “Macintosh HD”. See the screenshot below from a fresh installation of Yosemite. I assume it’s the same in El Capitan.