Ideally yes, because the system would be so robust that no new classes or even subclasses would be necessary. Unfortunately, I don't think that we are working with an ideal system. And a disdain for new classes does not mean that new classes aren't necessary, needed, or wanted. It's just a preference for avoiding addition.
I do agree. In a perfect, ideal world the classes and systems would be so flexible and adaptive that we wouldn't need as many new classes. And, in that perfect world, people would always get the new options they wanted, there'd be enough pages in books to satisfy everyone, and all the new options would be perfectly balance.
But the world isn't perfect.
New options aren't always balanced. Often far from it. And introducing new classes - which impact the entire game at all levels and interact with every other feature in the game - can be greatly imbalancing.
And there are a finite number of pages in books. Content you include comes at the expense of other content. Just looking at what's already been done, WotC chose to publish the Purple Dragon Knight subclass rather than something else. To give the fighter a fourth subclass rather than the bard or the druid a third. And a full class will come at the expense of a half-dozen subclasses.
New classes bloat the game more than any other aspect of the system. Because they can impact every round of every encounter of an entire campaign. They define characters.
They're a big part of how characters introduce themselves. When new players sit down at the table, they identify the other characters primarily via class. It defines the character and sets expectations. The more classes deviate from the expected fantasy tropes (or classes common in other RPGs or MMOs) the harder it is for those players to "get" the other players. It creates narrative dissonance. Gamers know what fighter/warriors are, and they know mages/wizards/sorcerers. But the more classes and adjectives you add the harder it is to picture that character. If someone says they're a vishkanya overwhelming soul kineticist* what does that mean? What do they look like? What do you expect at the table?
(* This being a speculative character I planned to 5th level for Pathfinder Society before I stopped playing in that program)
Classes also define the world. The PHB introduces monks, so monasticism and ki are assumed in every D&D world, and DMs have to find a way to justify kung-fu.
Every time you add a new class the Dungeon Master has to retroactively find a place for that class in the world. Suddenly this whole new profession that didn't previously exist now does. Warlords are easy in this respect, but other classes are less so. How would shamans fit? Mystics? Shapeshifters? Invokers? Dragonfire adepts?
So, yes, as a personal rule I push back against adding any new classes to the game.
I'm not someone arguing from the position that the warlord sucks. I think the concept of the class is a little weak for an entire class and thematically it would have been best as a fighter subclass, but agree that as is, the fighter is a poor fit. But I'd argue the same thing for the concept of the shaman, saying it should be a druid or cleric build (which, as written, are probably also a poor fit).
If this were 3e or 4e or Pathfinder I wouldn't even have bothered reading this thread. Because there was so much content, why not have a warlord? Have a warlord. And a shaman, assassin, ninja, shapeshifter, and dragonfire adept. Don't like something? Wait a month, they'll be more!
But now… we're getting class content once every two years. And even odds whatever the fall book is, it'll have <100 pages of mechanics. Likely closer to 50. Devoting six pages (or more) to a class whose concept is thematically weak *and* already in the game is a heck of a lot.
I'd have similar reactions to a magus/duskblade/swordmage class or a spell thief or an avenger class being added. We already have something in the game. It's not perfect but it does the job well enough. Give us six new subclasses that add something entirely new that isn't in the game at all.
The sorcerer and warlock were both introduced in 3rd edition, so they were only a part of two editions. The sorcerer was part of PHB1 in 3E but was in PHB2 in 4E. The warlock was part of PHB1 in 4E, but it definitely was not in 3E. So we are only talking two editions.
And they tried to remove both the sorcerer and warlock for 5e. They tried to fold them into the wizard and make an overarching mage class, and I was all for that change. We don't need a separate class for each origin story of how a spellcaster gets magic. The difference between a sorcerer, warlock, and wizard is basically the character's origin story. It's their background. It's mutant vs radioactive accident. It doesn't matter to the party.
But the playtest version they release only had the wizard and they didn't show how it would work with the sorcerer (and it had some non-generic class features), so I think many people rejected it too early.
And prior to that they tried to differentiate the two by making the sorcerer the gish class. Which was also rejected...
Furthermore the Warlord was in the 4E PHB1 and its spiritual predecessors were in the Miniatures Handbook (the Marshall) and the Bo9S. But the Warlord was in a PHB1 as its own class and not as a subclass or alternate class.
If we're counting the marshall as the warlord we can also count the spirit shaman from 3e which became the shaman in 4e. Or the ardent in 3e and 4e, and the cavalier from 1e, 2e (a kit), 3e (as the knight), and a 4e "subclass".
To say nothing of the assassin from 1e, 3e, and 4e. I could go on.
There's lots of classes with a legacy.
The difference is, of course, the warlord was published in PHB1. That's different… but still an arbitrary distinction. It's picking something that distinguishes the warlord and then inflating that in importance to justify the class.
One could just as easily pick the assassin and cavalier as they were created by Gygax. Or the ardent because it comes first alphabetically. Or the ninja because they're the most popular. Or the shaman because they're in World of Warcraft. Or the summoner because they're super popular in Pathfinder and would appeal to Pokemon fans.
You can find a reason to justify adding any class.
