The Game Boy has a Z80-like processor, though. Generally, Z80 instructions take more clock cycles to execute than 6502 instructions, so the clock speeds are not directly comparable.
For the same reason that they also include symbols for many obsolete (dead) languages and writing systems, as well as (per a comment above) a character used by the 1959 IBM 1401 computer (https://github.com/shirriff/groupmark). The need to be able to discuss a certain technology in writing does not disappear just because it is out of general use.
Some of their home computers competed pretty well.
The Atari 8-bit series (400/800) had a significant chunk of market share in the early 80's. Not among the top three, but there were so many incompatible platforms in those days, and Atari 400/800 was one of the more common and well-supported ones for sure. http://arstechnica.com/features/2005/12/total-share/4/
Then, the ST didn't do so hot in the US, but here in Europe it was a well-known platform, nearly as popular as the Amiga. Roughly 75% of sold Atari ST's were sold in Europe.
Most famously, nearly every recording studio you'd care to name would have ST's in the control room well into the 90's and in some cases early 00's, due to their built-in MIDI capabilities.
I'm happy to hear that gaming works well, and apparently my decidedly older CPU (AMD Phenom X4 965) supports the technology as well, which is interesting to learn.
However, my main reason for needing Windows is for music recording and mixing via Cubase and other DAW software. This requires really low-latency access to my USB and PCI sound cards.
Does anyone have experience with running applications like this in a VM? Is it feasible?
I would be thrilled if I could finally move to Linux or FreeBSD entirely and just keep a Windows 7 VM, all sandboxed up with no Internet access, just for the music recording.