This is a tricky thing. Facebook's business model, and its value proposition to advertisers to a large degree depends on oversharing, and your "Likes" are an example of this. If somebody asked me if I wanted my email subscriptions broadcast to all my friends, I would say "heck no." But if nobody agreed to share their subscriptions, then how would advertisers get word of mouth?

So they phrase it a bit differently. You don't subscribe, you "like." And your likes and dislikes are a part of your personality, which is something you want to share with your friends. The subscription is just a side effect of liking, and it allows marketers to use your name to spread their brand among your friends and acquaintances.

If they just called a spade a spade, it would be a disaster for them.