Are there any disadvantages of not to letting baby have a pacifier? Like affect their brain development?

From what my view, if baby like a pacifier to self soothe & stops them from crying, why not give them? If they cries for a long period of time, it really stress them out. Even for adults, being stressed up is not a good thing. As babies, they know they're feeling uncomfortable or what, that's why pacifier would give them comfort & helps them to feel better. If they are in a good mood, i am sure they will be happier in playing & exploring. From what i see from my son, he loves his pacifier but he is very fast & smart, he knows what he wants or don't want. I believe that he's actually faster in learning stuffs. Not the best, but still, not slow for his brain development. Yes you might need to worry about weaning them off the pacifier. But when they're ready, i am sure they will chuck it one side & not need it anymore. I hope my experience helps.