I think what scares some people is the idea of regimentation. Starting kids at daily practising whether they want to or not. Successful music teaching at this age doesn't say "you must play this scale over 10 times a day if you want to get any better" but instead says "playing music and singing can be fun why don't we try this?" My kids have been taking music lessons since my oldest was three. Then older kids in the class starting carrying our baby around with music. They enjoy and we enjoy it.