Another reason that plates are fine to stack is that they are all the same – and this means that you won't one of the plates from right down the bottom rather than the ones on the top. If you have enough space then you should keep all unique items in separate piles, however if you want to stack your smaller plates on top of your bigger plates because you don't have room then this is a common method people can use to save space. Stack larger plates under bigger plates in your cabinets of course as this way your towers will be less likely to topple and you will only have to lift the small pile to get items from underneath.
One kitchen cabinet is normally enough to store crockery like plates and bowls and if you have a couple of shelves this will be sufficient. Another will likely also be used for pots and pans and these are some of the most difficult items to stack. Unfortunately they are all different sizes and usually you will not own enough kitchen cabinets to avoid stacking them up.