To each their own ...
I don't understand your response. It didn't really add anything to the conversation.
The suggestion that a sling would be a good accessory was met by your response that it depends on the type of shooting you're doing. Why does my suggestion that shooting at an Appleseed event (which is taught using a sling) need a response? This thread was asking for opinions on accessories. If you have an opinion why someone wouldn't need a sling or why someone shouldn't shoot at an Appleseed, please elaborate. Your response basically says that people have opinions, but we all know that.
As far as why someone might want to shoot at an Appleseed, I gave a link to their website. To elaborate, they are a non-profit organization that teaches revolutionary war history and sling supported shooting techniques. Off-hand, sittting/kneeling, prone, using a sling. They also teach good shooting practices to help you be a better rifleman (or woman or child). They can help new shooters or people that have been shooting for decades possibly learn something new (as long as you have a teachable attitude).