The reason Oregon could do it is they basically confiscated the entire land, nearly at once from indigenous peoples who lived there. Then 90%+ of the natives died from disease, poverty etc.

When Maine land was “settled” by westerners (Europeans) it was more piecemeal grabs, and the “state” was across a large distance somewhat indifferent to what happened in the Colonies. By the time it was much of an idea the English Common Law was the norm and the Native peoples were dead from disease, poverty and wars.