Because it forces people to look in those forums. Then you get forums with more appropriate content. Eventually the forums will even out and become better used. The best way to deal with it is to go through each new forum each day and / or share on FB
"I thought you had crowbars?"
"LOL crowbars, what is this, 2007?"
"while on the chairlift your only goal is to chug as many pbrs as possible" - winelips