It’s actually easier to answer that from the ‘who wouldn’t benefit’ angle. In reality coaching isn’t for everyone. Sometimes it is more appropriate for someone to deeply process and heal the past before being fully able to focus on creating an inspiring future. Counselling has a more relevant place for that need.
Also, I’ve been known to refer to ‘uncoachable’ people (sorry not very pc). What I mean by that is, sometimes, even though a person may genuinely believe they want to grow and move forward in some areas of their lives, they are actually quite ‘happy’ being miserable. Literally there is too much benefit in their current (stuck) situation to really commit to shifting it. Someone needs to be willing to move forward in order to be ‘coachable’.