Bug reports are a little different than the product itself. I guess my take is that yes, if you needed it fixed because you are using it, then it makes sense.
But in the case of documentation, by the time I figured things out and see that the documentation is wrong, I no longer need the docs and I know what to do.
Documenting something you've just figured out, for other's benefit if not your own, is a pay-it-forward (or golden rule, or reciprocal altruism) approach: behave such that if other people behaved likewise, you would benefit.
But in the case of documentation, by the time I figured things out and see that the documentation is wrong, I no longer need the docs and I know what to do.