I don't think most technicians of the day foresaw the need to have these handy. When these Macs were current, they'd do what current Apple techs do--swap the board out with a new one. Even 15 years ago, most people seemed to repair their bad boards (including those which probably had bad caps or something similar that we now fix) by swapping them out.
Plus, the average tech probably isn't as into schematics as some of the specialists on this forum are. Most of them probably aren't really even trained in that department. (The same goes for CS guys). I'm pretty sure most IT certs don't require it.
Speaking of teaching, am I the only one bothered by the fact nobody has changed the title of this topic to "horizontal" stripes yet? Maybe it's just my educator tendencies...