Guide writers are only human and can make mistakes, mistakes which don't get spotted until after adventures arrive on the live servers due to the random nature of combat rolls. We also have the fact that the devs have said that based upon the feedback on the test forums we the players have yet to discover all the quirks in these MCC ventures, quirks like if you accept the higher losses from not having all the buffs you receive better loot in the follow-on ventures.
FYI the DSO sim has Risi.