I think your under estimating how incredibly good at "stacking stones" these cultures where.

Protzen, Jean-Pierre. "Inca Quarrying and Stone Cutting."Journal of the Society of Architectural Historians. 44.2 (1985): 161-182. Print

Protzen, Juan-Pierre. "Who Taught the Inca Stonemasons Their Skills? A Comparison of Tiahuanaco and Inca Cut- Stone Masonry." Journal of the Society of Architectural Historians. 56.2 (1997): 146-167

Here is my source material. In it it goes over the extreme tolerances and incredible craftsmanship of the Inca and Tiahuanaco. It's not like laying brick or stone masonry (also difficult) we do with mortar today.

Also these structures are made by a bunch of people working over years and in the Incas over vast distances. All done with out written language or at least one we fully understand. (I am aware of quipu) So they had the infrastructure and advanced enough society to train and standardize there building techniques.

Tiahuanaco are considered more advanced than the Inca and their collapse predated the founding of the Inca empire by roughly 600 to 500 years. Not saying they couldn't of provided some sort of inspiration for the Inca. But it also makes them more impressive and proves my point.

You should actually read the wiki if you're going to cite it.