That usually comes down to product and business decisions, not the algorithms. Facebook (like Pandora and many others) falls into the same trap of optimizing too much on top of their algorithms. Instead, some gentle prodding in an interesting direction is usually enough to prevent a bubble while guiding exploration.

I'd argue that without some guided exploration it's much easier to fall into your self-made bubble. For example unfriending people on facebook, or listening to the same 5 artists on Pandora.