Another "why not"

The North American Indian tribes, with the possible exception of Calusa Indians of southwestern Florida, didn't use sails on their boats. Which seems a little odd; there are plenty of lakes which would be easier to get around on if you had a sail you could unfurl when the wind was right. The Egyptians used them to go up the Nile, and I presume sails would be equally useful going up the Mississippi or the Missouri. (You'd have to learn tacking, but that shouldn't take too long.) Maybe Superior isn't the best place to learn about sailing, but there are other lakes.

But the most famous Indian water vehicle (hardly the only one, though) was the birchbark canoe, which while nice and light for portaging isn't ideal for hooking a mast on. That would require a heavier frame, making the result a lake-only vehicle.

My Better Half pointed out that the Indian fishing methods were shallow water technology, and so there'd be no great need to go out far and deep, where sails would be most helpful. While they made plenty of fishing nets, I don't find any reference to long and deep nets for deep water fishing. If the populations were low enough that shallow water fishing was adequate to provide the supply (but Cahokia or Aztalan?), then the additional effort wouldn't have been worth it. So why bother with sails.

We stalled there. Maybe somebody has more information?