So the magic of Power Query is instantly apparent and tangible to basically any Excel Pro. They can immediately see how PQ will save them oodles of time and anguish.
The benefits of DAX and relationships, by contrast, are less readily-apparent on first glance. Portable/re-useable formulas that enable rapid iteration, the answering of “emergent” questions in near real-time, as well as a “subdivide and segment” capability? Or how about multi-data-table capabilities that provide an integrated and convenient view across many different sources of formerly-siloed data? These concepts are simply alien to the longtime Excel user, even though they are MONSTERS in terms of their biz value (as well as time-savers and anguish-reducers). None of the impact “lands” up front because it can’t adequately be contemplated until you’ve started DOING it.
Rob’s looking at this from the standpoint of an educator helping train people with Excel expertise.