This dude is using tools that were supposedly not available thousands of years ago.
He’s not building into solid rock, it looks more like some kind of clay texture.
Ok, power tools cut through mountains like butter so that a single man can do stuff like this today.
https://www.youtube.com/watch?v=fyfxB_SqWtc
So it's possible. But who's paying for large temples to be cut out from mountain faces in today's day and age? We're achieving engineering feats that would make ancient people think that WE'RE the aliens. And there are people who think it's the other way around? We are where we are today because ancient people mastered the art of stonework back then. Forgetting or ignoring that and attributing it to aliens is disrespectful to our history.
Discussion
Your question was about being able to replicate the feats of our ancestors today, and I'm saying that you can. If you want better proof, take up the art and carve a baller temple into a mountain yourself.