Then that is legitimate! The point of decluttering is to have space for the things you actually want to keep, and if the desire of your heart is to have three thousand pens, then go for it :D

I have way more books than any organiser person would approve of, but that is what I want space for. So I try to make sure I'm not keeping books for the sake of it, and am otherwise entirely at peace with my seven full bookcases. But my pens are just sitting there taking up space I could be using for something else, so I do want to go through them at some point. It's all entirely personal, isn't it.