Hadn't thought about it from the perspective of support contract profits, but they also have their friendship stick firmly planted in technicians via the semi-required training since as you indicate the manuals are deficient.
At some point network vendors switched manuals from engineers documenting features whitebox to educated techs documenting features blackbox.
There's a clear transition for docs produced after 2008, prior to which more care went into tech notes and interpreting technologies -- after you're lucky to even get a complete set of steps and caveats without having to cross-reference bugs, release notes, old-manuals, new-manuals, draft manuals, reference manuals, licensing manuals, the inevitable errors that appear in the logs, and of course the configuration guide where this should all be in the first place.
At some point network vendors switched manuals from engineers documenting features whitebox to educated techs documenting features blackbox.
There's a clear transition for docs produced after 2008, prior to which more care went into tech notes and interpreting technologies -- after you're lucky to even get a complete set of steps and caveats without having to cross-reference bugs, release notes, old-manuals, new-manuals, draft manuals, reference manuals, licensing manuals, the inevitable errors that appear in the logs, and of course the configuration guide where this should all be in the first place.
In short, yes, this.