Brooks Landon has already provided the explanation in the final paragraph that you've quoted:
just as the thinking of Hemingway’s old waiter is infinitely more
tired and less active than the thinking of Faulkner’s boy, the
sentence each writer constructs is intended to hit us in very
different ways for very different reasons. Start cutting out words ...
Restating the claim in the question,
writers like Joseph Conrad should have structured their books like
decks of PowerPoint slides,
which would have made them
The first point to make,
though it may seem a little cheap,
you haven’t tried it:
your questions here have all been
written in standardly presented prose
Compare the two sentences:
Dolphins are humans of the sea
Dolphins are like humans, but they live in the sea
The former is a metaphor, the latter is a simile.
If you look at the former sentence closely and think of its actual meaning, you can see it's technically a lie. Dolphins do live in the sea, but they are not humans.
The second sentence is true: ...