...and your comment communicates a much more believable idea than the one PG is attempting to communicate, which is not quite the same: " I think writing that sounds good is more likely to be right."
Your comment also makes clear that this requires that the writer is attempting to make a true core point, rather than (for example) convince people of something it would be convenient for them to believe. If you are dealing with writers who are using their powers for ill purposes, then the skill of the prose may well be inversely correlated with their truth.
When you write well, you iterate. When you iterate, you improve both the prose and the core point -- because you crystalize ideas further.
This makes improvements in these seemingly perpendicular directions counterintuitively correlated.
Ironically I found this specific PG essay uncharacteristically obtuse. This could have been much shorter.