https://www.nal.usda.gov/collections/stories/three-sisters

It specifies the cultural application but broadens the temporal.

(To be more direct: not every first nation practiced that technique.)

Now that's a correction.

"was" vs. "is"

It's more labor intensive, especially for corn. You can't just run a big harvester over the field, someone has to go out and pick it.

Profit margins and prioritising short term gains. :(

It's possible that otherwise good combinations don't line up in terms of season and require crop rotation as opposed to polyculture.

The Iroquois are the Haudenosaunee. The latter is the more respectful and culturally appropriate term.

https://en.wikipedia.org/wiki/Iroquois

Haudenosaunee ("People of the Longhouse") is the autonym by which the Six Nations refer to themselves.[23] While its exact etymology is debated, the term Iroquois is of colonial origin. Some scholars of Native American history consider "Iroquois" a derogatory name adopted from the traditional enemies of the Haudenosaunee.[24] A less common, older autonym for the confederation is Ongweh’onweh, meaning "original people".[25][26][27]

There is a tense change. The second person is saying the technique is still used by those tribes today.

I read it as criticising reductionist views of the many diverse nations that existed in North America before Europeans showed up and decided that the whole continent was Terra Nullius.

To this day a significant number of US high school American History textbooks only discuss the tribes in terms of their interactions with European invaders, and shy away from anything that might make them look like they were ever legitimate nations. Referring to them as 'Native Americans' instead of by name also has this effect.

Aren’t the named tribes a subset of native Americans, so it can be true without the original statement being false?

The original statement implies the technique was widespread across Native American groups. It's almost certainly false for the ones here in South America; there's a lot on terrace farming and slash-and-burn, but AFAIK nothing that resembles the companion system of the three sisters. (I wonder if it's due to the prominence of subterranean crops. Taters, yucca, sweet potatoes.)

The Haudenosaunee/Iroquois and the Cherokee/Tsalagi being related hints me it was something they developed.

I believe it's the verb tenses. Instead of it being a historical fact, it's an ongoing practice of an ongoing group of people

Well, “Native Americans” means everything from whoever lived on the tip of today’s Argentina all the way to the Inuit. So saying “native Americans” when it’s actually just two tribes is wrong.

Edit: Wikipedia says the technique was used by ‘various’ people.

I think that's why there's a smile in the last square.