"Why not quit using petrochemicals and just kneel with a weed puller.
It's very effective, involves moderate exercise, and your kids and dog
can play without worries."
Maybe because it's a hell of a lot easier and practical to use
chemicals. Few people are going to get out on their hands and knees
and dig out weeds in any decent size lawn. I'm not in a proponent of
using chemicals excessively, or where not needed. For example, I
wouldn't use a weed n feed product unless the lawn was full of weeds,
because it puts a lot of weed killer all over the whole lawn, where
it's not needed. For a lawn with a moderate amount of weeds, using
spot application of chemicals is fast, effective and relatively safe.