All God’s creatures got a place in the choir
Some sing low and some sing higher
Traditionally, technical manuals have been written as if they were the only source of information on a product. Of course, the manual was never really the only source. There have always been neighbors, friends, colleagues, retailers, user’s groups, and professional associations to learn from as well. But access to these other sources of information was not universal, and those groups themselves had to learn from somewhere — information had to propagate through the network before it became available to the ordinary user, and the propagation was usually quite slow. It was reasonable, therefore, for users to look on the documentation as their principle source of information, and it was reasonable and necessary for the documentation to be written as if it were the sole source of information on a product. Not any more.