There's something that's missing from this dialogue. A simple observation:
Tabletop games aren't just a game. It's time spent with your friends. It's an investment of creativity, time, and effort. No one has spent ten, fifteen, twenty years playing Monopoly with their friends every weekend. No one really remembers a good game of Uno or Clue ten years later, but a good campaign? A good adventure? A good climactic fight? Your favorite character? Your first character death?
And because of that emotion that gets attached to those concepts, people want to protect it. Because something different has some sort of implication of "Well what you did wasn't as good as it could've been because these rules are better." Sure, no one ever says that to your face, but perhaps that's the way people feel when "Surprise, new edition!"
Let's take an example of a class that you played the first time in the game. Or, the class of your favorite character. Now, you may have not played that class in years. But if that class isn't included in the PHB, you might feel rejected. That whoever made the edition just put a bullet between the eyes of your character.
Is it irrational? Hell yes. But is it childish and wrong? No.
Nostalgia and emotional attachment. It's a helluva thing.
