I don't believe that chub or perch do the same job so effectively. Perch and chub will seemingly only take a lure when hungry. If they feel peckish and there is a dead fish lying around, they'll find it and remove that potential source of disease as well. Clubs trying to maintain over-stocked waters without an effective predator to remove any fish showing the first sign of disease, are asking to have their stocks wiped out completely. Male pike don't usually grow to more than about 10lbs.
Big pike regulate the number of small pike.
The number of small pike available depends on maintaining a healthy stock of prey fish. Mess about with this balance at your peril. Particularly on a smallish water, the death of one or more large pike can signal a disaster. The population of jack pike explodes as each try to grow bigger faster than their competitors, in order to occupy the now vacant position at the top of the food chain. Unless the water is exceptionally productive, this explosion of small jacks can cause a crash in the prey fish populations.