They restrict driving on mountains to stop erosion. These climbers are driving metal bolts into a beautiful mountain face. That's got to be doing some harm as well as not looking very nice.
It's more because it's El Capitan. It's a special place. I get why climbers feel attracted to it but it's more important that it be protected than people, in ever increasing numbers, get the pleasure of climbing it. Look at what's happening at Everest. The feat's been accomplished, no need for everyone else to do it too.