I think we overestimate the influence these type of fishing boards have. e.g. I live next to the Notty. The number of people fishing nearby varies a lot, depending on the river conditions and how well the fish are biting. It doesn't at all depend on anything posted on the boards---I have never seen anything specific. Everyone knows about this spot----fishermen come from TO, Hamilton, all over. They've been coming for years(more like decades) long before the existence of fishing boards.
Just remember how prevalent texting is and how quickly word spreads----he told 2 friends, the told 2 friends etc, etc, etc. The very definition of exponential increase.