That is the Mentor system if i remember the name correctly. Although they could be more strict on the scaling if they wanted to implement it into eso.I remeber in Rift that high levels could join in the dungeon finder, I really hated it because it became a walk over. As long as you can turn off joining with high levels I don't have a problem with it.
But I don't want to be forced to be matched with a high level player though.