Azzy
ᚳᚣᚾᛖᚹᚢᛚᚠ (He/Him)
And the opinion of 5e.
"Every adventurer is a member of a class. Class broadly describes a character’s vocation, what special talents he or she possesses, and the tactics he or she is most likely to employ when exploring a dungeon, fighting monsters, or engaging in a tense negotiation. The character classes are described in chapter 3."
The special talents(mechanics) are listed separately from the description of vocation(fluff), both of which are what comprises that class. You can tweak it a bit, but if you completely upend either the mechanics or the fluff, you are changing the class into something else.
Broadly describes. Like I said, it's a starting point, not an end point. There is nothing that says that you cannot sttray from this fluff. Nothing. Heck, even the lead designer, Jeremy Crawford, encourages reskinning. So, no, your hardline view is just your opinion.