The algorithms on the Wikipedia page quoted actually solve a different problem. And they can do that in constant space.

So if someone tells you that one item in the stream is repeated so often that it occurs at least p% of the time (say 10%), then these algorithms can find such an element. But eg if they are multiple elements that occur more than p% of the time, they are not guaranteed to give you the one that occurs the most often. Nor are they guaranteed to give you any meaningful output, if the assumption is violated and no element occurs at least p% of the time.