I feel like the author is looking at using amendments as a way to implement legislation that is permanent. Our Federal constitution is fairly concise, whereas some State constitutions are so easy and readily amendable that legislation gets codified in almost every session [1]. The challenge with doing this is that the constitution itself converges into just another body of law.
[1] https://en.wikipedia.org/wiki/Constitution_of_Alabama
Edit: Instead of "permanent", "decisively" would be more appropriate. A constitution that can easily be amended can just as easily be un-amended. A response to this comment said "way to settle national controversies" which seems far more fitting than what I originally wrote.