Is it true waterproofing outside walls is not necessary?

The importance of this may depend on who you ask. But if you stop to think about this - you dont want to cut corners protecting outside walls of your home. There are pores in those walls - and things can get in if you dont protect them, such as bugs, air, dirt, water, outside pollution and more. You dont want to have to worry about your foundation in later years - so why take chances now. Outside protection is definately a good idea for your walls.