Why did it take so long for a (g)tar(1) man page to come into existence?
<grin>
People (on average) just don't like to prepare good documentation.
"It's boring" seems to be the general attitude. But, in fact, it
is actually very *difficult* to do! Unlike code where you can
"see if it works" (as one measure of your success), documentation
is much more subjective and prone to lots of assumptions on the
part of the writer ("Oh, I thought everyone *knew* that so I
didn't bother to explain it...")
And, most documentation tends to be written after-the-fact...
describing (often incompletely) how something (appears to) work
instead of how it is intended to work. (there is a subtle
difference, here, but one that, IMO, dramatically affects the
style of the documentation)