Is this not what EVERY founder of a denomination does?
No, and I already explained why. But I believe I can state it more simply:
The Roman catholic church claims they have the God given authority able to make laws which bind up men, laws which are not found in the Bible.
The Rabbis traditionally believe, as the Pharisees did, that they also have this authority.
Mormonism also gets into this, but they put a different spin on it by claiming they have new prophetic revelation which contradicts the Bible (Not just the book of mormon, but ongoing "prophecy" by their leaders).
No protestant, by definition of why they were founded, believes they have the authority to bind another man by a law of their own creation by claiming it to be the law of God. Because, by definition, the Bible is their authority of what God expects of us.
A protestant will say "God wants you to do this, because the Bible says so, and this is why I can prove the Bible says that".
What you will not see them doing, which sets them apart from the other religions I mentioned, is: They will not say "God wants you to do this, because our denomination leader says so, or historically this is what our denomination leaders have said".
Where your confusion probably stems from, is the issue of differing interpretations about what the Bible commands amongst protestant leaders.
What you must recognize, is that there is a categorical difference between someone who says "I believe the Bible says this, and this is why" versus someone who says "I cannot be wrong when I declare the Bible says this because I am head bishop of such and such denomination; because my position in this denomination means I have the authority from God to declare what is true". The later kind of excuse doesn't fly in protestantism. But you will find it in Roman Catholicism, Mormonism, and even Rabbinical Judaism.
The later is, by the way, why we have Karaite Judaism. They reject Rabbinical law and believe they are only obligated to follow what is written in the Bible, because it is God's law.
One well known Karaite ended his Rabbinical training because he realized one day it was wrong when the Rabbi told him "If there is a disagreement between what God says and what the Rabbi says, then God is wrong". He had enough spiritual sense to realize the absurdity of that statement the moment he heard it.
Exactly. Every denomination has leaders and rules that those inside generally accept, but there's the strong tendency to denounce the leadership and rules in another denomination or religion.
As I just restated, you seem unwilling to recognize the categorical difference between someone who makes an organizational rule that they acknowledge is only the rule of men, versus an organization that tries to declare their man made rules are actually the decrees and commands of God to His people.
Almost no protestant leaders historically even try to do the later, and if they do they are always universally outcast by the rest of protestantism as being un-Biblical cult leaders.
By definition, once you engage in that kind of behavior you no longer fall under the label of protestant, based on the reason why protestantism was founded, because you are no longer appealing to the Bible as your authority - but instead are appealing to your own authority, and claiming your authority comes from God.