Bacon's quote speaks to the idea of how one needs to exercise caution in their associations.  The idea of "costly followers" as ones that increase connectivity, but decreases individual effectiveness though making "wings shorter" is a type of warning that Bacon offers in his essay.  Bacon is stressing that the individual embrace a more analytic approach to the selection of people who one chooses to take into their inner circle.  Bacon's context is not to exclude association.  Rather, he is emphasizing the idea that individuals must exercise a sense of judgment and analysis in selecting who will is amongst them.  The definition of such terms is important to Bacon and his analysis:

Ordinary followers ought to challenge no higher conditions than countenance, recommendation, and protection from wrongs. Factious followers are worse to be liked, which follow not upon affection to him with whom they range themselves, but upon discontentment conceived against some other;

Bacon continues this with the idea that individuals can earn their keep with another person, that if one demonstrates their loyalty on a consistent basis, they can be taken into confidence.  In typical scientific form, Bacon suggests that one must not be swayed by the initial claims to friendship:  "It is good discretion not to make too much of any man at the first; because one cannot hold out that proportion."  Bacon's conclusion in the essay resides in the notion that "there is little friendship in the world."  It is precisely for this reason that one should avoid "costly followers."