When I worked for a large daily newspaper, the rule of thumb was most of the the readership will change about every 7 years. Probably about the same for forums, as well as for other media, like Farcebook,
or Twit...ter.
Perhaps sooner, as attention spans seem to have gotten shorter. But, "Social media" seem to have replaced the telephone party line (Remember those?) for information gathering.
Also, you wrote for "The Omaha milkman." Allegedly, he was someone with a 7th grade education, (How they arrived at that, I never understood.) and a short attention span, which is why, using short "attention getter" words ("Prostitute" doesn't grab the attention like "Whore!")
we put all the pertinent facts that fit in the first two or three short paragraphs, and the lesser stuff later.
It seems like every so often, a new crop of enthusiasts comes along, many being newly enthused about the whole subject of weapons...long range shooting, reloading, ammunition, knives, swords and thew "new and improved stuff we see all the time in gunzines...asking many of the same questions we all have asked at various stages of our involvement in this "Fine and Pleasant Madness".
Sometimes, the Search function does not work very well, so a lot of the same questions get asked. Some of the "old timers" run into a problem they haven't experienced before, and ask questions, which may or may not produce useful answers.
Some sites have developed their set of devotees, and they don't like newcomers, for one reason or another.
So, hopefully, mature and pleasant sites like this one will continue, for pleasure as well as information.