The 7.1 discussion got a few things right (e.g., need space behind the seating to be effective), but unfortunately started from the mistaken premise that a 7.1-speaker layout is somehow tied to discrete 7.1 content, when that hasn't been the case historically.
Fosgate started selling consumer 7.1 pre-pros in 1986, Lexicon in 1988. By comparison, discrete 7.1 content didn't show up until 2006 (two decades later). Heck, even 5.1 content didn't show up (on laserdisc) until the mid 1990s. So the number of channels in the source material had nothing to do with the number of speakers used for playback.
Even in the Pro Logic era, content was 2 discrete channels, carrying 4 matrix encoded channels, typically played back over 5 speakers. Again, the number of channels (matrix or discrete) had nothing to do with the number of speakers.
Many of us have who have been going to movies since the '70s have seen commercial theatres go from 1 surround channel (Dolby Stereo) to 2 surround channels (discrete 5.1) to 3 surround channels (Surround EX) to 4 surround channels (discrete 7.1), all while maintaining the same number of speakers in their surround arrays. Again, the number of surround speakers those theatres used had nothing to do with the number of channels in movie soundtracks.
Considering that history, it was odd to hear consumer 7.1-speaker layouts (which have been around for a quarter century) discussed in terms of something as recent as discrete 7.1 content, when that's never been the point of a 7.1 configuration.