Happily! I'm not a fan of fear mongering either, but I AM a fan of science and of people having all the information! Like I said, I'm not trying to upset anyone, just to share information! Everyone should of course do whatever is right for his or her family!
This site explains it well (it's a cloth diaper site, but it has good illustrations of how detergent works) http://www.fluffloveuniversity.com/sourced-science/
Here's one of the sites that explains the difference between soaps & detergents. http://www.detergentsandsoaps.com/soaps-detergents.html
And my personal favorite: a collection of people who have been using homemade detergent who "stripped" their clothing and the dirt that came out! (A strip is the soaking process used to strip away hard water mineral build-up or soap build-up (not to be confused with detergent) that is adhered to the fibers and get them clean again.) http://www.fortheloveofclean.com/laundry-love/the-bad-the-worse-and-the-ugly/testimonials-from-former-users-of-homemade-soap-photo-gallery/
As for the warranty/washer damage, there are plenty of anecdotes, but I recommend reaching out to the maker of your washer. I confirmed today with the manufacturer of mine (I have an LG) that using soap would void the warranty and that over time the soap would damage the washer because of the difference in chemical compounds between soap & detergent.