One of the links (on Fusion) points out that GHC in particular has a lot of optimizations and rewrite rules for folds and many Prelude functions written as simple recursion also include optimized fold representations to suggest to various stages of GHC's optimizer.

As with so many such topics it seems an interesting spectrum between clarity and/or aesthetics and potential performance optimizations. Especially because it often seems like one of those "learning curve flips the clarity/aesthetics preferences" because at some point of familiarity folds can be faster to read than trying to reason through an explicitly written recursion.