Bard in S tier? Druid and Wizard in A tier? "a cleric will never have the tanking abilities or damage dealing of some other classes"?!?!

First, Bard is not nearly versatile enough to rank S tier, Spell Secrets or no, and they've been rather consistently underwhelming IME.
Second, Cleric has Spirit Guardians on full casting, easily making it the best tank and one of the best damage dealers.
Third, Druid is a master of single target DPS in the form of summons (wolves, velociraptors, flying snakes), and also land based CC, and Wizards are CC gods. Something the author has clearly never seen.

Also Monk in D-tier, not Ranger. Shaking my head.