This really isn't true. LNT is very explicit in that concentration of use at established campsites is very much in keeping with the overall philosophy of minimizing impact in the backcountry.
From the LNT Website:
So concentration of use can be in accordance with the LNT principles, depending on the context.
- In popular areas:
- Concentrate use on existing trails and campsites.
- Walk single file in the middle of the trail, even when wet or muddy.
- Keep campsites small. Focus activity in areas where vegetation is absent.
- In pristine areas:
- Disperse use to prevent the creation of campsites and trails.
- Avoid places where impacts are just beginning.