There is no consensus answer to that question. Some say yes it prevents sone amount of gunk from getting into the engine and causing excess wear and tear, some say no it's not needed and others think it may extend the life of the engine so why not do it.
It doesn't hurt anything unless you forget to empty it routinely (usually with each oil change). That is many peoples argument for why it is not included by the manufacturer. If you don't empty it it will cause far more damage then not having one and many people don't bother to change oil on time let alone remember to empty a catch can.
For me I don't feel it's necessary and have not pit one on but I don't feel it does any harm.