That move surely being relevant to pre-1980 computers? Alex surely isn't short for Alexander Graham Bell?

Of course not! (Yes, sometimes ol' FTB answers his own questions. We all should, if we have an ounce of curiosity.) It must be this Alex Bell: https://www.chessprogramming.org/Al...

16.Bg5 is a natural move, developing White's last minor piece and connecting the rooks. However, it allows Black time to castle to safety, leaving White worse. Therefore, 16.Bg5 is inferior.

The computer's ability to set and maintain (w/a Q sacrifice) the pins on the Nd7, Qc7, and Rc7 is the much more impressive feat. Such play is broader in scope, offering Black more replies to address. If Bell took the entire resulting sequence into consideration, then 16.Nxe6!! as the instigator of the entire game-changing maneuver (from losing to winning w/simplification - all of Black's heavy pieces are removed) is a much bigger deal.

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Realize that microwaves and remote control toys were still a big deal in 1980. Computers were appearing in labs at work and school in the mid-80s, primarily word processors/printers (improved typewriters) without the internet. Most people did not own their own personal computer at home until the 1990s. ClarisWorks, anyone? Our early PCs required an internet connection through the telephone land line. In fact, while on the internet using a land line connection, it was not possible to receive a telephone call; a busy signal was received by the caller -- which frustrated many a caller! The reliability and speed of PCs vastly improved when the cable connection arrived before the turn of the century.

FYI: People did not have pocket cell phones until about 2000 -- then it was an explosion of public demand. Cell phones and Satellite phones operate from different sources. Satellite phones existed earlier, but were not mainstream.