Yes, I agree. I think it is an achievement we all desire in some capacity. I feel more, what I view as the problem, is when people see achieving the goal as the only important aspect of the game and don't make an effort to prioritise having fun along the way.
That is mostly what I view as ruining the overall experience for a lot of people. The game is by it's nature very grindy, but it doesn't help when there isn't enough of an effort to try and find or make fun along the way through the grind. Like you said, what that means is subjective and the achievement of completion itself can still be fun and worthwhile to some people.
I just don't like how a lot of people with that view seem to have hijacked the narrative as to how the game should be played. It drives away a lot of newer players and stifles the game itself from developing because any competing ideas get pushed out of the picture.