I honestly get both sides of this kind of argument.
Any RPG with roughly the same premise is D&D to me. DCC RPG, Index Card RPG (the fantasy version), Dolmenwood, Shadowdark, XCrawl, Black Sword Hack, Pirate Borg, Warcraft, World of Warcraft, Daggerheart...they're all D&D to me.
And yet...I'm still salty about things like the stats being in the wrong order (it's supposed to be Strength, Intelligence, Wisdom, Dexterity, Constitution, Charisma) and AC going the wrong direction (it's supposed to go down, not up).