Because, even closer to the beginning, in the real first sentence of the article (by which I mean, the first sentence after the title), it says, "This is a mildly edited transcript of my JSConf Australia talk."
This is not an example of the "big text chopped out" paradigm from magazines, it's an example of the, "each slide contains a brief of the most important part of what you'll be saying while that slide is being displayed" paradigm from conference lectures.
The problem is those slides hinder the readability of the actual article.
For a reader, you get into the rhythm of the writer's voice, only to be interrupted by a giant image of text every other paragraph. It's a battle between just skimming the slides, or trying to read the content.
If the author had just swapped out the "loud" text images for subtle headers, the article would actually flow.
And therein is also seen a limitation of using someone else’s blog engine; on large (wide) displays, this would be better done with the slides on one side, and the speech on the other, appropriately lined up. But you can’t do that when you’re using Medium for the post.
Because, even closer to the beginning, in the real first sentence of the article (by which I mean, the first sentence after the title), it says, "This is a mildly edited transcript of my JSConf Australia talk."
This is not an example of the "big text chopped out" paradigm from magazines, it's an example of the, "each slide contains a brief of the most important part of what you'll be saying while that slide is being displayed" paradigm from conference lectures.