i have to admit i felt much of the same thing when i joined. i was even slightly enraged. i was like, wtf, where are all the infjs! and it sucked for a while before i found a bit of a place. but then, most of the people i have actually come to interact with on here happen not to be infj, and they're awesome. for example you can tell straight away by what April wrote how thoughtful she is. and also i'm pretty much totally myself here, i'm allowed to be almost as deliberately complex and difficult as i like and actually get understanding about it. i am in fact not marginalised here at all. so i don't think it's too rough really.
a number of the infjs who use this board, are also very quiet and sensitive, and they emerge more as you watch. their thoughts are all over the spectrum. not that i've really talked to many of them, but i have noticed them. if you're not into one or another of the voices here, regardless of type, forget about it, there are plenty of others to listen to.
i have thought that this board actually depends on other types to survive . i don't think this would work as a pure infj board, i think it would probably just go silent and dead. we can be both very intense and very shy. i think the other types help to moderate the extremes.