It's not only that solutions decay, though that's true, but also that the search for improvement itself becomes recursive.
When you identify something can be improved, and fix it, your own fix and every individual step of it now become the new thing that can be improved. After the most fleeting of pauses to step back and appreciate your work, this becomes your new default.
Indeed I often look back at my own solutions and judge them more harshly than I would ever judge anyone else's. Why? Because as the article says, I know much more about how it works. Cracks increase surface area by a lot. I know about a lot of the cracks.
I wrote a blog post [0] about this mindset getting in the way of what you care about in product development which you might enjoy, if you enjoyed this article.