Is it a common misconception that the line formations used by the British in the Revolutionary War were a result of them being honorable or stupid, rather than being more advantageous than less orderly formations?
I've heard elementary school textbooks in the US often claim this.
I am specifically interested in any reliable sources explicitly identifying a common misconception.
If I understand what you are asking: their formations had nothing to do with honor or ignorance of tactics. I've answered this question similarly here. In the link I provide a book by Matthew Spring that would answer a lot on your questions on this misconception. Speaking as an amateur historian, I would be leery on books that dictate the British army or any army use their tactics based on honor or stupidity. No army then fought with the broadest strokes of tactics and changed them whenever terrain or enemy formations presented itself.
The British knew and used guerrilla like tactics quite often in the Revolutionary War as they had learned it in the decades prior. And as the years went on in the war, they moved away from the tight closed formations with three ranks and gravitated to more open formations and two ranks. In addition, if they were not put into a pitched battle the soldiers could use cover from trees, rocks, or fences to fight with. By the mid point of the war, many of the regiments battalion companies knew light infantry tactics such as using file partners and rapid movement.
Even if the large and tight formations seem dumb they had reasons to employ them. One part of its use came from the capabilities of the land pattern musket and their most effective use. Their are some misconceptions about the muskets as well. They are not the "can't hit the broadside of a barn" gun that people think of when the word pops up. With trained and experienced soldiers, they could hit marks at around the 100 yard line. The 23rd Royal Welch Fusiliers drilled in Boston during the occupation and the men practiced their shots with man sized targets set out on stages in the harbor.^(1) So they are indeed using moving targets to practice with. Even with individual accuracy, it would also depend on the stress handling capability of each soldier while under fire. More experienced and hardened soldiers would of course have an easier time for the most part.
The other reason of the tight formation with three ranks came from the formation's defense against cavalry. Three ranks of bayonets allows sturdy defense to be formed against a charge. However, once the British noted that the Americans rarely had cavalry to use in the war they put in orders to change to open orders and two ranks. This is not to say the American army did not have cavalry but it was not the main element of the army. In addition, neither was it for the British but that's another topic entirely. They had their reasons to use both in the war. Totally loose formations would not work in most of the battles, unless the terrain allowed for it.
I went through a lot on the link and it is quite thorough. If you have any questions from it, let me know.