As was just said, if you are given the opportunity to "customise" then all possible combinations get tested and compared and you only end up with one answer the most efficient/strongest build that everyone from then on must adhere to in a party scenario. So all that would change is instead of Party finder saying "clear only, ilv105 restriction" it will now be "clear only ilv105 must have xx skill equipped" You may have customisation but whats the point when all it does is get you kicked from parties by not following the most effective build.