In any group there is some "monotony of thought" that those in the group believe. Sometimes these groups are voluntary like Church or the Republican Party, but sometimes these groups are simply happenstance such as socioeconomic background or neighborhood. And as humans we often have the tendency to believe that since we are rational that all other rational humans think as we do.
And it can be shocking to find out that this is not the case. For example Dragon Dan 31D obviously disapproves of some of my thoughts that I have written down. Maybe he is offended that I am not an unconditional cheerleader of the encroaching police state or "pro-military" that it left him unable to reason critically about what I said, instead of who I am when I say it. And this is normal because both Dragon Dan 31D and myself serve in uniform, and after all there really is a large uniformity of thought in the Armed Forces.
So what happens when people find out that other people don't think like they do? History tells us that groups will splinter because of it. The Catholic Church had a "schism" with the Coptic Church only a few hundred years into the history of Christianity. The "Bull Moose Party" ring a bell? Sipsey Street Threepers verses others?
Which makes the Declaration of Independence, Articles of Confederation, and the US Constitution so unbelievably miraculous. That a large group of intelligent, independent thinkers, could recognize that together they were smarter than any single one of them alone. That through rigorous debate a better decision could be reached. And that is the success of staying the course towards a group goal, even if you don't have "groupthink" to keep you together.
The goal is freedom. Internal dissent is completely fine as long as we keep working towards freedom. The moment someone says, "screw you guys, I'm going home" we have been divided. And a house divided shall not stand. In the words of Franklin, "if we do not hang together we shall surely hang separately."