How accurate is a Civil War Smoothbore Musket at 100 yards?

According to preeminent RUclips comment scholars, the smoothbore musket is utterly useless beyond the range of 75 yards, “a total crap shoot,” as they say in technical language. And people who disagree with this deep historic wisdom are truly pseudo experts, misleading the community with BS that they yank out of their butts.
But… is it possible that this conventional knowledge may be wrong? Could somebody be wrong on the internet? Could a RUclips comment actually be proven to be incorrect through experimental archaeology?