People have been saying that as long as popular music have existed. Jazz was considered dumb and unsophisticated, crooners were considered dumb and unsophisticated, rock music was considered dumb and unsophisticated.
Each of these genres just discard previous measures of sophistication and introduce their own. The article have an interesting observation about "vertical" vs "horizontal" songwriting. Newer music is just different.
Kendrick Lamar is not dumbed down compared to Bon Jovi just because he doesn't change the key before that last chorus.