One of my children was dummy obsessed, another his thumb and one was happier without anything. Both those with something to suck spoke earlier than the one who was happy to be without. The one with the dummy had it forcibly removed by my mother...she was unhappy from then on. I'm not sure she ever recovered but maybe she would have been less satisfied with life whatever the circumstances.
When my Grandson used to come to me, once he reached a certain age, I wanted the dummy to go during the day. However, although I persevered, his parents didn't. As he was non-verbal I got quite exasperated but it turns out he was autistic and the dummy had nothing to do with it...according to the SALT. When he becomes overwhelmed, I am now happy to let him have the dummy although he is over 3 because it does sooth him. We are looking for something else, but until we find it, the dummy stays.