Not sure why people would say that. Perhaps it is a an anti-slot receiver bias, accusing Edelman of being a 'system receiver', or a sports talk host attempting to have a hawt take? Sounds like bitter fans of other teams that would prefer to forget the 28-3 game.
All one had to do was look at 2016, when Brady missed 25% of the season. Edelman had 98 receptions for 1,106 yards that year. His only season with more yardage was last year (barely, with 1,117) when there were few other genuine options for Brady to target.
In the first game of 2016 with Jimmy G making his first start Edelman had 7 catches on 7 targets for 66 yards, and the next week (JG/Brissett) he had 7 catches on 10 targets for 76 yards - despite the Pats running the ball more often than they threw it.
Edelman's numbers went down in week 3 but that was due to #3 Brissett making his first NFL start and the run/pass play calling becoming an absurd 2:1 ratio with 39 rushes and only 19 passes. The week four stats are useless due to both QBs injury status and the last minute change of starting QB.