Code that does what it should is rarely read. Until you need to change it.
And it may not be changing due to it being incorrect. If an attendant system gets replaced, you may have to change all the other systems it has touched. Business requirements may have changed. Stakeholders may have changed.
There are plenty of reasons for code to change beyond there being a bug.
I don’t think you read the whole article. I had the same thought as you from the headline, but they gone on to state that good code is so easy to read when you need to make changes that you don’t have to go through it multiple times to make the required changes.
Code that does what it should is rarely read. Until you need to change it. And it may not be changing due to it being incorrect. If an attendant system gets replaced, you may have to change all the other systems it has touched. Business requirements may have changed. Stakeholders may have changed.
There are plenty of reasons for code to change beyond there being a bug.