I don’t think that’s quite what was happening. It was more a case of, lacking any specific “point of play” one was suggested.
Completing the mission, getting the loot, killing the monster….these are all pretty common goals of play in D&D, though they’re certainly not specific. I don’t think using them in an example to explain how there are goals beside having fun is an attempt to define specifically what the point of play will be.
I think it was more emphatic than that, but taking this- I still disagree.
A lot of D&D is similar to a pencil factory during a graphite shortage- pointless. And that's fine!
There doesn't have to be a point, or a goal, to the play. It can satisfy a lot of different desires- it can be something as simple as "entertainment." In that manner, asking what the point of getting together with friends to play D&D (or other games) is similar to asking, "What's the goal of watching Sunday Night Football tonight?" I dunno? Because it's there? Because it's a pleasant use of my time?
I think a lot of this is from conflating different approaches to the hobby; to use a very simple example, I have a small group of adult friend I get together with occasionally and we play board games. The goal of it certainly isn't to win; in fact, while we have fun and try, I think anyone that was overly competitive wouldn't be welcomed back (trying too hard is gauche, you know?). Because there is a large component of the social activity that is orthogonal to what we are doing.
What some people try to do is assume that everyone has the same interests in terms of advancing specific play objectives. In other words, how do you play "better." How do you make the experience "better." How do you better align the rules and the RPG and the theory and the everything else to maximize the experience- to make it "better." There's nothing wrong with that!
...but that's also not why everyone is playing TTRPGs (I would go so far as to say that it not why the
majority of people are playing TTRPGs).
And the friction occurs because of arguments over silly things, usually definitions. Usually jargon. But those silly arguments are just papering over the underlying disagreement that cannot, and will not, be resolved. Because different people get different things from the games we play.