When you behave with perfectionism, you basically want to make things perfect, or not make them at all. Why is this bad for you? Because more often than not you will get blocked and paralyzed if you try to make things perfect. Even if you manage to make them perfect at one point, it might be too late to reap the rewards from it.
The author then lists specific examples, such as never launching your new website because the structure isn't quite "perfect."
Makes sense to me. I can definitely see where the author is coming from. In my experience as a writer, as well from my dabblings in video editing, I know only too well that you could spend an eternity making minor changes to your product that, in the end, only serve to please yourself -- nobody will notice or care if that scene is cut by another two frames or not.
Similarly, I can also see the benefits of avoiding perfectionism from a business perspective, as there have been a couple of occasions at Marketing Breakthroughs where the client should have just "let it be" and published the website or brochure or whatever instead of making minor change after minor change after minor change. Trust us, it's good enough to go. Delaying it only makes things worse, in the long run.
Of course, saying that is easier than actually putting it into practice -- making things perfect is a natural goal to strive for, after all. Maybe just not the most realistic one.
PS: Happy Thanksgiving!