1.i think it's necessary to do so,for it can make your products more widely known by people,and think your products are better than others.
2. advertisements could just think as a reference , we should not fully believe them .
3. They produce a lot of false information,which is likely to mislead people to buy the things they don't need.
4. I think it is meaningless to do so,for it can only make young to compare with others in money field.
~O(∩_∩)O