There's some sense in filtering.

Of course--the alternative to self-labeling isn't sacrificing your personal criteria. I might not have understood you correctly, because I'm not sure whether this is agreeing or disagreeing or a tangent.

but do you really want to date someone who doesn't?

That actually makes me flinch a little, because I've spent a lot of time on OKCupid thinking "It seems like everybody else has defined things which they go out and practice and spend money on and share with their friends. I don't have anything like that. Am I just too boring? : \" I suppose that's more not having a discrete hobby than not having interests--but my interests are much more about the way I live than what I go out and do. I don't think I actually am boring, but I'm afraid I read that way, because I don't have a thing which I do.

I only feel I know someone when I know his personal philosophy, but that usually takes time to come out.

Indeed. I might have said "worldview" instead, but they're probably different angles on the same idea.