I mean, it is kinda true. The D&D cleric was born to counter a vampire character and all of its stuff came from justification of countering said vampire characterCompletely untrue.
While you could claim the idea that the inspirations for the cleric and paladin are the same, claiming that there are no clerics in the literature means ignoring history
Anywho, I'm all for new classes. Warlord/battlefield commandery type who does the leading and not necessarily the fighting and Psion are the two big archetypes with some more room to them, but I could see other things being split off. There's enough Witch classes out there that I'd argue there's enough demand it could be looked into, the idea of a summoner sort also has a lot of promise (Even if I know balancing it would be a nightmare), and that recent thread on assassins has gotten me pretty on-board with it being its own thing
On the removing monk/sorcerer stuff from earlier, I do disagree. Firstly, Fighter is not so strong an archetype it can consume everything else in its wake, getting rid of the stuff split off from it like Barbarian or Paladin just weakens those archetypes. Secondly, I'd argue the solution is to make sorcerer more mechanically its own thing, as the fantasy arcetypes of "Born with magical power flowing through your blood" and "Make a pact with an entity for power" are so far from each other I find the idea to mechanically combine them moreso a failing of D&D in making them mechanically distinct. I remember people making a push for sorcerer to be Con based which, would be interesting and fitting with the theme