I don’t think I have ever thought about what happens to a sentence when there a lot of -ings, but now that Clark mentions “it takes on a progressive sense,” I understand (31).
“Prefer the simple present or the past.”
Clark insists there is nothing wrong or bad about using -ing verbs, like there is something inherently repulsive (most of the time) with using passive voice. Rather, he thinks too much is too much. A well placed -ing verb can spice up a paragraph of simple past or present verbs.
It is only a problem when overused. So use them sparingly. Use them beautifully.