Why Steemit needs a "Friends" list
Rumor is that sooner or later the people of the Steemit community will get to know each other. When that happens it might be important for people to categorize their social contacts in a way which is human friendly. In addition to this the "friend" tag could have a specific meaning to the blockchain and act as a social filtering mechanism for people who don't want to be contacted by anyone except for their friends. People on the friend list could be designated as the people who can make private contact without paying a tribute and this could act as spam control in an attention economy.
People tend to form cliques in a place like this. Steemit ultimately will become circles of friends, and friends of friends, but this information could also be useful at a blockchain level if certain information is only shared privately between friends, or friends or friends, and this could also be used in future broadcast features, future live chat or live stream features, and so on. Today we just have followers, and while this has some value in the business frame, it doesn't have much meaning in the personal frame.
Friends is distinct from followers
Followers probably don't really personally know the people they follow but like their content, while the people followed probably don't personally know who follows them other than they are fans of their content. This has value in terms of the kind of content to create in the future.
Friendship is a bit different. Friends might not really care much about the content from the position of fan, but might care about the person producing the content. Friends might want to support their friends content by voting up their friends and in my opinion this behavior should be allowed and encouraged. It builds community to allow friends to support friends, and the blockchain would reveal who our friends are based on statistics such as upvotes, private messages sent/received, total bandwidth spent communicating with, and so on.