I don’t know *why* they buried it but I’m glad they did! Have you looked at photos of the carvings? They’re in pristine condition. Look like they were done last week. It’s an astounding find and most people say “gobble gobble what?” when you try to tell them about it. ;o)
I have guessed that the pillars with “T” shape were holding up roofing timbers. The carvings do not appear to have been heavily weathered the way the Sphinx was, from rain and flowing water.
I wonder if the monoliths themselves might be remnants of some even older civilization; their hard square edges and the detail of the carvings are very sophisticated. They almost look like some sort of antediluvian highway support pillars.
The carvings are interesting to contemplate as they are not carved into the stone monoliths, but sit in relief on the surface. That required an amazing amount of carving to produce the monoliths; 12,000 years ago.