With the Lactose intolerances, the way I understand it, we have a certain amount of bacteria or enyzmyes (forget which) in our digestive system that can process milk products. When we eat more than we can safely digest we have our problems. Lactaid and other products can help with that digestion (if taken at the right time) but there is still a point where too much is too much. So, as said above, it's about moderation.
On the other side there are folks who have milk allergies. That is not the same thing as lactose intolerance. If folks have a milk allergy you'd be surprised by home many things have lactose or other milk byproducts in them. Ugh.