GOOGLE+ and the 18+ plus rule; does everyone think all teenagers are idiots!

I would like to use GOOGLE+ but am not over 18.  I get this impression that 18+ people think all teenagers are immature and should not be allowed on the network.  I would like people to explain why this is the impression or if I am just misinformed. 

Cheers 

~Supercgeek from Techtainian.net