I've noticed this myself... but I do remember something, though. Back in the late 90's - mid 2000's most forumers (on any forum) where 18+ and the regular forumer was in their mid 20's-30's. Finding teenagers was a rarity, I'm not saying they didn't exist, but they would only limit themselves to boards related to videogames. Most gamers on forums were also over 18+. I've been a regular on forums since the early 2000's... I was just 12 years old when I first began my internet activity and I could notice the age differences.
Back then, teenagers (or kids) were not really attached to their computers, or the internet for that matter, as they are now. Now the Internet is more accessible than it used to be and kids are getting their hands on high end technology making things easier for them to be full time net-goers, hence the ever growing teenage activity on the net. Adding to this, forums are dying do to facebook, tumblr, etc... and other social medias. Despite the decline of the forum, you can probably see why a majority new members are teenagers. Yet, this new membership is not gonna bring the forum culture back to its HEYDAYS. Most popular forums nowadays only have certain sections that are active anyways.
This new wave of kids don't really understand the Anonimity culture that came with the FORUM/CHAT/ BOARDS. Putting your real name, picture and e-mail address on forums for everyone to see was almost non-existant, and only old people in their 50's would do such thing. Nowadays these kids ask for your picture and real name because they don't know the FORUM ettiquette.
I do miss the days of the forums... I had great times. Now forums have this post-apocalyptic vibe. It's depressing.
[ Edited by WINTERFRONT on 2/14/2013 12:18:41 AM ]