My son unlearned all sorts of things in pre school that he knew concretely and abstractly before then. Including: whole word reading (went for a ball of whatever when they started insisting he do it phonetically), mental maths (slowed right down due to counting to 20 every single day when he could already do double digit addition and subtraction in his head), writing (they insisted on daily colouring to strengthen writing muscles), telling the time -they only did this in Gr00 (age 4 - 5) and only to half hour. so he forgot that he already knew how to tell the time. He forgot his left from right which he had instinctively known since before age 2. It was even on his silly report card! So I am fully of the opinion that if they need to count let them with whatever method they enjoy (numberline, manipulatives, fingers toes whatever) but if they don't need to then don't make them!
