Your quoted text from Amazon or the book is word for word what is on Ready.gov.

In general, a water filter is my go to if I plan on needing additional water on an outing. Purification tablets are my backup while on the trail or what is carried in an emergency when no additional water is planned as needed. By planning ahead, you never need them, but it is good to have them available.

I never boil. Takes too long and utilizes resources I plan for use elsewhere. Filters are instant, weigh less than a stove or extra fuel. And when I take a stove, I only use it for cooking. Yea, you can use an alcohol stove, they have their place. But why waste the fuel. Modern filters are small and don't have the bulk & weight issues old ones did.