I am tolerant of new players who are trying to learn their role until about level 50. If after that basic expectations are not being met, more often than not I choose to leave the party rather than be vocal about the issue due to the way in which some players react to advice regarding mechanics such as aoeing 3+ enemies or pulling multiple packs at a time.

If I see someone is at least making an effort, that's ok. But single pulling in current levelling dungeons just isn't the sort of gameplay skill I expect at someone of that level, along with knowing what various markers mean. Using skip potions does not excuse one of this responsibility.