Why are there two ways to "like" a question? Favorite and upvote. What's the difference? When should I do one and when the other?
You upvote a question/answer because it's a good question/answer. This usually gives the author reputation.
You favorite a question because you want to be able to find it again (maybe you have the same question). You can find your favorite questions by going to https://meta.stackoverflow.com/users/131235?tab=favorites#tab-top
For many users like me a favorite is mostly a private bookmark and badges based on favorites are a kind of nonsense.
That means my bookmarks are a mix of great links I really want to favor and some short time bookmarks I remove a few days later.
The true question is why are so many people using favorites as private bookmarks.
Lets take a look at Firefox which creates great bookmark entries with a lot information. But there are no simple sql like query tools who return a simple result like give me all bookmarks which are tagged with 'SO' and with 'MyQuestion'.
Search machines and Browsers just don't target at advanced users.