It does need the saying. There will always be newbs arriving wondering how to pull the most out with the least effort. Or worse yet as you mentioned, the legit ones that get a good reward on that first post and then little for the subsequent ones and can't understand it and just shrivel away.
You have to be made of stern stuff to stick it out sometimes!
I have seen it time and time again, I struggled to find a good one for an example as I don't tend to follow new users right away unless they are exceptional (or Urban Explorers!)
I have seen it countless times too. Just the nature of the beast. Tis like a grand game and some people are just not very good at games!
Can't beat a bit of morning philosophy :OD