Two reasons Facebook's data points to algo determined newsfeed is better; addictiveness based on time spent and interaction, more display ads.
They can control the FB experience and show "relevant" ads because they create the relevancy by choosing what content to display around the ads. The real time newsfeed can't be controlled, humans uploads can't be predicted. More$$$ from advertisers by owning and crafting the story for every user every time.
They hoped no one noticed.