DDO is no different. If you want a challenge then PUG. PUGs are where the challenge is because you never know what quality of players you are going to end up with and you never know what decisions they will make. It makes for a chaotic time which increases the challenge and unpredictability of the run. People sometimes mention that PvP is where the fun is because you have a human AI. In a PvE game PUGs are where the fun is because you have humans in your group that sometimes behave as if they are trying to get the group killed (though usually not on purpose). It accomplishes the same goal as PvP (namely unpredictable behavior that makes for an exciting time) while still getting to work together as a team.