The picture above is NOT on the Main Trail. The Mountaineers Route goes up the North Fork Lone Pine Creek, splits off the Main Trail at the first main stream crossing. It is not a trail, and the picture above shows the people doing it were OFF ROUTE. There is an easier place to climb that slope.
Ideamani: I'm not sure when you are going, now. But right now, small storms are adding a little snow to the trail. May can be like that. When you go, let's hope it is a few days after a storm, and you can follow others tracks. Unfortunately, I understand that this time of year, in the area between Mirror Lk and Trail Camp, sometimes tracks go all over the place, made by people losing the trail and looking for a better route.
Don't try to follow the switchbacks above Trail Camp. But do try to watch the most traveled path below.