This sounds so silly, I mean who cares whether any pilgrim ever saw a blunderbuss? Just because this flared muzzle weapon was invented much later than the time of the pilgrims, what difference does it really make?
But have you ever seen a drawing, around Thanksgiving, of men with blunderbusses over their shoulders, on the way to church in the very early days of America? I can't remember an illustration of a pilgrim carrying a musket, a very different weapon, and pilgrims did carry these to church.
Only reason I mention this at all is that because some illustrator, a long time ago was given the assignment of drawing pilgrims, and drew them this way and forever since then they were drawn this way. Guess the man or woman looked in an encyclopedia at illustrations of old weapons and just chose one. Others, maybe hurried by a deadline, followed suit.
I have pity on most preachers. They have a hard job and often without much support from congregations, either financial or by way of meaningful friendships. But quite often these men quote other men, perhaps in a hurry to write a sermon.
Some congregations are "easy" and really don't care about hearing reused material. Others are allergic to ideas that are new to them. Better to play it safe and follow an old track.
But imagine a man giving us a totally new idea that is, new to us. How brave he would be, and how adventurous. Such a man would have my admiration, and if he was not fired, his congregation would also.