The problem is this:
There are two games running simultaneously in wow. There's the ACTUAL progression game we all know and "love" (the 'three pillars'). And there's this weird mirror version of it. For each of the three pillars you have this shadow experience running alongside it (heroic v mythic dungeons; lfr v raiding; battlegrounds vs rbgs/arena). Heck even torghast doesnt have one difficulty level. Im trying to think of one feature that has a single difficulty level, that requires some competency, and that incentivies players to step up, and the only one i can think of is the mage tower. Perhaps arena (skirmishes and arena in general feel a bit more niche).
So talking about tooltips or the adventure journal misses the point a little. No player NEEDS to learn how to play the game beyond the absolute basics. There's no challenge in game that doesnt have a simultaneous easier version of it. This isnt to bash any players for choosing to just play the game how they want. The problem is that there's really no incentive to step out of your comfort zone and move into the more challenging content.