WHY IS IT THAT YOU CAN FEED A BABY UNTIL AROUND 18MO AND...?

no one says anything, but if you see an 18mo old with a bottle, its so horrible? i know denists say bottles are actually ok until age 2! i know the conforms to the mouth, and doesnt cause a structual problem; however, what about the playtex natural latch that conforms to the mouth also? oh, and pacifiers, how are those ok for past a yr, but a bottles not? how is any of this different? im not talking about all day. sippy cups used during the day, and bottles just for before breakfast and after dinner. some babies just like the comfort, and the soft spout sippy cups arent the same, neither is a thumb!