[KoRn]

At first, I felt the same as you do, but I believe there aren’t many ideal locations to place large observatories of this kind. I also believe they are overstating this a bit. I’m SURE they won’t be literally “destroying” a mountain. Most likely just clearing a building/compound location. I doubt it would be much different than clearing off a place on a mountain for a very large home.

[BenLurkin]

The set-up crew for the E-ELT blast looks at Cerro Armazones. Credit: ESO

artist's interpretation of the completed projrct