“Getting in is the hardest part”
I would respectfully disagree with the implication that higher aggregate GPAs at the most elite schools suggests a lack of academic rigor. At institutions where over 50% of matriculated students were HS valedictorian or saludadictorians, test scores in top 2%, ECs that indicate a history of engagement, top tier recommendations, etc you would and should anticipate a higher average academic result. The result of this vetting process is students whose performance merits on average the higher GPA.
If you cook with the most selective, high quality and freshest ingredients you tend to get the most consistent and best meals.