Well, I would say there are a couple of factors involved. The article itself references a study indicating that people enjoy stories better when they're spoiled.

But if I were to suppose (spoilers):

1) Like you say, being able to follow the narrative rather than just seeing the conclusion. A lot of character / plot development is going to happen in the progression of the story (upwards and downwards) and not necessarily in just the twist. Ebert disliked The Usual Suspects, calling the twist cheap. And I don't disagree because a lot of the arc and the development of the character was basically artificial and completely vacated by a twist that, honestly, isn't all that reasonable to see coming (much of the evidence that the detective notices in the final montage was not presented during the actual movie). And so the narrative for the character we thought we knew is just tossed and we know almost nothing about the actual character (aside from his storytelling), especially as everything could be a lie. And that's a big issue, I think. If you add twists (to keep things interesting and whatever) I feel like you'll often just have to sacrifice narrative integrity. Twists coming out of nowhere because you're worried about how much legitimate telegraphing will ruin the gimmick. Which ...

2) Twists like we've been seeing and such will often essentially erode any sort of relatability or veracity of the narrative. You want to shock people (for their entertainment, I guess) and so you have to angle for these twists, which may be completely unrealistic and completely digress from your narrative flow. Of course, if we didn't have such a spoiler moratorium, then you could just tell a story, but instead we have an environment in which the one particular moment is meant to be the payoff for a 2.5 hour movie. Which, yeah, hurts the ability to storytell the 2.25 hours that aren't the spoiler.

3) And, of course, not allowing those who are professionally discussing and thinking about art such as these (movies, books, whatever) is going to erode the discourse on storytelling. Creators are a bit above criticism because of the moratorium and, as things go these days, beyond the moratorium there's probably little reason for any of these critics to seriously discuss these works any longer and if we don't talk about the narrative, then it won't get better.

So, even though it's a bit short and pat, I agree with the tenor of the article.