An Inconsistency

The puritans who rule Saudi Arabia are busy destroying anything that could invite idolatry. Vast tracts of old Mecca and Medina have been flattened- to the despair of archaeologists and historians of Islam- and Mohammed's birthplace and the cave in which he composed the earlier parts of the Koran are under threat.

I respect the puritan mindset, but what I don't understand is why, if shrines must go, the Kaaba is spared? How is it OK to prostrate yourself before a big black rock but not to visit the house where the prophet was born? There's a lack of follow-through here.