Wow, really? You're right -- that does sound harsh.
We send our kids to preschool. We have zero qualms about it. For our family, it helps both school and home to run more smoothly.
DD went to preschool even though we were considering homeschooling her starting in K. It was a church-based school, only 5 minutes from our home, and reasonably priced. It was a fantastic experience for her and I'm glad we did it. She was an only child at the time, and we live in a rural area, so getting some time with friends was great for her. The school shared both our social/religious and academic (i.e., play-based vs. academic-based at this age) values, so I don't believe being with someone other than me did her an ounce of harm. She wound up (due to some unforeseen factors) going to public school for K-2, which was FAR worse.
Since we've started homeschooling, DS has gone to the same preschool a few mornings per week, for the same reasons we sent DD. And there is the added bonus of a little quiet, uninterrupted time for me to work with DD on school. I get plenty of one-on-one time with DS at other times. And the truth is, I am not great at the preschooler thing. I am much better suited to teaching/managing at an older level. I also work from home, and I know my physical and mental limits. Preschool DOES allow us to make sure EVERYONE'S needs are met in the way that best suits him/her. It's rather rude to insinuate that families who choose to use a preschool/mother's morning out program don't have the best interest of all their members in mind. We're all doing the best we can.