Most in the bodybuilding community are motivated by a desire to look a certain way, or at the very least to improve upon their physique and take more control of their appearance. Understandably, this often necessitates dietary manipulation. More often than not, individuals go through phases of caloric restriction to reduce fat mass (while attempting to retain muscle mass), alternated with phases of caloric surplus to increase muscle mass (while attempting to minimize fat gain). Competitive bodybuilders and physique athletes do this in an effort to be competitive season to season, and it is a necessary approach to make progress between seasons, and to step on stage extremely lean.
Unfortunately, this back and forth can often interfere with having a healthy, normal relationship with food. It is rare that bodybuilders, especially novices, are comfortable and capable of managing their body composition without being at either end of the spectrum. Maintenance is often seen as antithetical to the goal of bodybuilding; which is to always progress, in one way or another. Thus, the idea of not being in an assertive deficit or surplus is unfamiliar at best, or seen as a waste of time at worst.