You cherry picked one example of a tangled/messy block of code that they used to communicate specific idea around "left to right" comprehension and flow of the data using the new syntax. For that specifically it did a fine job.
But that doesn't mean that's the way you should be writing code in the first place, given it started with a mess and only used one piece of syntax to change it.
I will admit it's a poor example to open with. But for a design doc about exploring and debating ideas it's fine.
I don't think it's fair to say it's "cherry picking" to focus on the example they focus on themselves. They have a few other examples too, but I would say "I don't see how [NEW] is better than [OLD]" for many of those as well (and for some, I think the [NEW] is significantly worse).
Plus the doc is #1 on HN after all, which could IRL push it beyond a proposal stage if done right.
I also have a feeling this doc lists every sort of usecase, not because they are advertising it as "always the better version", but because it's a design doc that needs to factor in edge cases, such as using a pipe following chained function calls.