I’ve seen that graph before and have to say I’m baffled. Certainly, there must have been no popular support for such an idea in colonial times or just after founding the US. How, in the middle of that time period, did a majority of the public become such compliant milquetoasts?
There were the Quackers, and others. The frontier ended about 1890, and 1900 is when the Progressives started saying that the Constitution was outdated.
http://gunwatch.blogspot.com/2013/05/armed-citizens-and-modern-frontier.html