The reason that algorithmic feeds were introduced was essentially that Zynga and various heavy posters were killing Facebook (but mostly Zynga).
Back near the dawn of time, FB's feed was chronological, and that meant that Every.Single.Farmville.Notification showed up in your feed (and there were a lot of Farmville notifications).
This was actually causing real problems for Facebook, and they introduced an algorithmic feed to fix it. Back then, it was actually relatively simple, and mostly just ranked posts based on how connected you were to the person on Facebook.
Obviously things have changed since then, and algorithmic feeds have had a host of weird impacts, but a ranked feed is not necessarily bad in and of itself.