There’s a lot less room for a socially distanced queue than people think. The 6 feet isn’t just in front of and behind you, it’s to the sides as well. What is normally 3 aisles of switchbacks now becomes a single aisle. If you think about the queue space in front of the amphitheater, that’s around 15k sq ft. If each person gets 2 sq ft of space in that rectangle, you can fit approximately 7500 people in there. If each person gets 6 sq ft, though, all of sudden you can only fit about 2500 people.
It’s a massive difference, and managing guests behavior in a queue is already hard enough without social distancing measures.