While many (if not most) countries have national parks, the policies surrounding them are different. A simple thing like camping is often restricted in European parks, mixed land use is allowed so you are more removed from pure non human nature. As a result, the experience of visiting one may be vastly different - depending on what you are doing. American national parks are exceptional not because they are the only country that has them - which isnt true as you pointed out, they are exceptional because of the governing policies surrounding them.

I’d surely visit one, before I left, because the experience isnt going to be the same in any other.