Well said.Disneyland isn't a history museum. It's entertainment based on idealized things from history.
Frontierland doesn't have negative parts of history for the same reason a 50s cafe wouldn't have segregation.
Apologies to anyone who wanted to see the crusades at Sleeping Beauties Castle.
Disneyland is an escape, away from the negatives. Does it mean it's accurate? No.
Would I want to visit a place that recreated the worst of history? Heck no.