...snip...A lack of any infrastructure to get there. You make it sound like going to space is like walking to the store. ...snip...
Oh, that's an easy one.
They could have "ascended" either by buying a stairway to heaven or by "mastering the fermenting arts" and then farting all the way up to the skys.
Here's a proposal-
Let us all join in a moment mythbusterswards hoping they will descend and carve stones, settling down the issue. (*)
Now, on a more serious note... Those Tiwanaku folks... Yes, they created outstanding examples of art. There are masterworks, masterpieces out there, its a great piece of inheritage left by those who came before us. No questions about it.
Part of the fascination of it, I believe, is because it is different in terms of architecture style from the things we are used to see. Petra also has masterpieces carved in stone, intricate carvings, straigth angles, etc. But we are used to its style and its also better documented. Thus KotA will not argue for ascended beings (or other nonsense) being responsible there. He -and other woos- will put it under another labell.
Now, take a closer look at Tiwanaku. Can anyone find any piece of evidence for something really beyond its time? Oh, yes, KotA will argue for the shape of the blocks. Anything else? No.
What sort of advanced civilization capable of raising itself to the sky was that?
No glass windows.
No steel or aluminium tools, furniture, etc.
No copper wires.
No plastic tools, furniture etc.
No evidence for modern medicine in the graves of their citizens.
Where are the toilets?
Where are the kitchens with tools such as gas or microwave ovens, refrigerators, etc.?
Why no remains of cars or similar things?
What were their clothes and shoes made of, again?
Those guys at Tiwanaku, by the way, despite creating masterpieces of art and architecture, seemed to have no idea on how to build a round arch...
Oh, yes, maybe they ascended with all these stuff and had a super-duper environment repair program, erasing all the traces of their mines, oil and gas wells, power plants, carbon and radioactive isotopes signatures. Oh, yes, advanced technology can be indistinguidable from magic! Oh yes, this should be the explanation! Because you know, the alternative means all this babble about lost golden age civilization of ascended beings would be nothing but a fantasy. It would mean KotA's worldviews and beliefs are wrong!
It would mean his interpretations of ancient myths are wrong...
It would mean his alleged skills are not a good refference...
It would mean the mysterious star shaped objects he claims to have seen are not linked to past civilizations...
It would mean he wasted and is wasting a lot of time and effort for nothing.
(*) We know it would not actually change KotA's mind (as well as other woos'). They would just claim the results did not looked exactly like those stones from Tiwanaku, or it would take to long to produce the number of stones required to build a wall or that they cheated.