I think it has more to do with the expectations of kids buying these sets.
The do have to have the tipi, totempole, etc. That's 'real' to them - never mind if it's correct
.
If they were to leave out the tipi (for example) they would definitly get a lot of requests for it, or at least a remark that it's a pity they 'forgot' them.
It's the same with the horned helmets of the vikings. They didn't have them in real life, but still - a viking without a horned helmet isn't a viking to most people.
So ... they more or less had to make them. Although Playmobil has a educational value too - it's a toy that needs to be sold in the first place.
But I still think it's great to discuss and find what is right and what isn't.
Bogro