Earlier quoted context omitted.
Your citation does not support the "decisively predates agriculture" claim, and in fact refers to early agriculture at the site as one of the competing interpretations.
Göbekli Tepe was built ~11,500 years ago, and it probably isn't a coincidence that early agriculture was developed in the same area -- about 1,000 years later. The early agriculture reference that you mention concerns the fact that the was abandoned as early agriculture started to take hold: > Around the beginning of the 8th millennium BCE Göbekli Tepe ("Potbelly Hill") lost its importance. The advent of agriculture…
1. The site seems to be built with a plan. Maybe they did not use paper and pencil, maybe they were using some kind of sand table[2]. And there was a number of people involved, who were quite good at stone cutting, and on a large scale. Just have a look at central obelisk and pedestal [3] - those sharp edges, those smooth surfaces. Now, getting good at something requires daily practice, for a long period of time during which one would rather not go around for hunting. So not only there was a population of proto-carpenters but also societal structure to support them, at least for times of learning and construction work.
2. Even more unusual, the site seems to have been abandoned (evacuated?) in planned manner. Great effort has been made to cover it up with huge mass of soil mixed up with broken stones, as if to make it tougher against elements. This, for me, really stands out. AFAIK the norm is, when supporting culture "loses interest" in site maintainance (like, when all its members are dead), the site is being taken over and/or decaying and/or reused by next wave of humans. But not this time.
Quite fascinating.
[1] what I know is subject to change as time goes by and I get updates
[2] https://en.wikipedia.org/wiki/Sand_table
[3] https://en.wikipedia.org/wiki/File:Göbekli_Tepe,_Urfa.jpg
