Why did the Protestant Reformation give rise to so many splinter sects?

It seems in the centuries following the Protestant Reformation, the Protestant branch of Christianity further fragmented into possibly hundreds of smaller groups ( from the Lutherans to the Calvinists to the Quakers to the Baptists to the Methodists, etc). Why are there so many sub sects? As an atheist I see it as an example of religious people being inconsistent with their own religion just making up their religion as they go along- but could there be somthing within Protestant sub group of Christianity that lead to such a massive fragmentation?

via International Skeptics Forum https://ift.tt/2JftbLh