Do people need to know exactly what you're going through to be your friends? I'd say no, mostly because there's only one person who knows exactly what you're going through. If that's the only place you can get your friends, you'll be lonely for your entire life. It's also the fact that our different experiences make us interesting to each other. How many stories do you think conjoined twins can tell to each other? We do need shared experiences too, because that's a huge part of building friendships, but when you meet someone for the first time, you've been through none of the same things, not exactly, and you need to be able to move on and up from there to become friends.
Mokalus of Borg
PS - Someone who's been through all the exact same things as you would be boring.
PPS - Though someone who understands nothing about you won't relate to you at all.