This is a great example of just how much goals of play can differ from table to table in 5e. What you dismiss as the superficial play-acting level is something I actively prioritize as both a player and a DM.Sorry, but this isn't actually having that character DO anything, it's just play-acting. Which is one of my complaints about these systems -- they don't encourage actual changes in play, they encourage superficial changes at the play-acting level.
Sure, D&D games play similarly to each other in comparison to the whole universe of RPGs as a whole. But is that really the most useful yardstick to use when evaluating the claim that 5e is flexible enough accomodate divergent styles of play?Sigh, 5e isn't that flexible (nor is D&D in general). Everyone here is playing pretty much the same way, with small differences that are imagined to be large so that 5e is flexible enough to accommodate them. But, everyone is expecting the GM to drive the game, everyone is expecting the GM to be in charge and have the say, and everyone is fine with play constraints that are very tight on players and very loose on the GM. This latter is usually what's confused for flexibility -- the game's core mechanic is "GM decides" and so different decisions is viewed as those big difference and flexibility -- but the choices are still in a pretty small bubble of play for RPGs as a whole.
From my standpoint that claim is justified so long as there are 5e tables with styles different enough from each other that each group would not enjoy the other table's style--the styles are divergent enough to be incompatible. I don't think it matters to the validity of the claim that there are other games with styles that are conceptually divergent, rather than merely incompatible.