It's completely understandable why you feel that way.
As Zhaorin says, the wiki isn't exclusive to minors. It's is good place for anyone to find a community/more about themselves and different identities. It's somewhere for all LGBT people, not just under 18s, and there is a pretty significant part of this community that is over 18./nm/g
As Zhaorin said as well, a DNI would probably help a lotto prevent 18+ accounts from interacting with you./g
This is such a large resource for LGBT information - imo it's good that it isn't entirely on the shoulders of a group of teenagers (though a lot of staff members are under 18, including this account). It is also generally a positive thing for us to have some people around who may be better-equipped to handle some topics/situations, etc minors may not feel they should/can interact with subjects that are generally considered 18+ issues, especially with no support/input from anyone who isn't under 18./nm/g