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
It's called many things, but the most common terms seem to be multiperspectivity (what Wikipedia uses), alternate point of view, multiple narrative, and switching point of view. Multiperspectivity, however, seems to be a bit of a broader term - it refers to more than just literature.
It does seem to be a fairly common style (at least now) - I know Rick ...
I note that the two authors you cite are both English writers, and so the issue you bring up deals with how the English language acquired its extensive vocabulary.
While many of the words used in writing English are words inherited from Middle English (I will refer to this as stock English), a large part of English vocabulary comes from borrowings from ...
To answer the question implied by your "I feel": The sentence in question
His constant practice of padding out a sentence with useless epithets, till it became as stiff as the bust of an exquisite; his antithetical forms of expression, constantly employed even where there is no opposition in the ideas expressed; his big words wasted on little things; his ...