This article is excellent. I can say from my experience that a slide that calls out key takeaways is 10x more informative than one that doesn't and leaves that to the user to infer.
Having said that, while doing due diligence, one parses the key takeaways and ensures that the data confirms it. Then one looks at the data again to see what has been left unsaid.
In the example, I might ask them how is their "profit per user" trending? That metric is clearly absent and puportedly they removed their free-tier to increase the "value per user". Is their experiment succeeding (or showing early signs of a trend towards success)?
At the very least, the key takeaways make this process of discovery more streamlined. I am not saying you should try to answer every possible question in the key takeaways, but if it addressed the most important ones, you have achieved the communication objective for that slide.
