Maybe this is indirectly addressed in the paragraph "Start paying undivided attention to important events and interactions"? The author writes:

> How many times have you walked away from a conversation having no idea what was discussed because you were distracted by your phone? “You can get impoverished memories for past events because you were never really there in the first place,”

Maybe we used to be more "present" in the past, and therefore formed better memories? And now, with constant distractions literally at our fingertips our brains have less and less opportunities to form "sharp" memories as there is always a distraction pulling us away. And, as time goes by, due to lack of training and/or laziness, our brains actually get worse and worse at forming proper memories even when a distraction-less event is encountered?

Just a hypothesis.