For those who remember Chicken Pox, almost everyone got chicken pox. To the extend any NPIs reduced transmission (e.g. keeping kids out of school), the primary result was delaying chicken pox or avoiding major outbreaks, and delaying chicken pox may have been a bad thing.
As a different analogy, if you have a Windows XP system in the Internet, it will get pwned. If you update it to Vista, you get a worse UI and it still gets pwned. Sometimes half measures are much less than half effective.