It's not hard to see from the first couple of chapters why DEC PHIGS and PEX were routed by GL. I mean, the main factor was that Jim Clark took a VLSI design class from Carver Mead and Lynn Conway, doing a 3-D accelerator, and founded SGI with it in 1982: https://ai.eecs.umich.edu/people/conway/Impact/FundingaRevol...
But really, Fortran for examples? In a 1989 book?