Aunty, your web source is WRONG. The proper way to launch a boat is to back it into the water and then remove the safety chain and strap. This procedure is approved by the USCG and USPS and appears in Chapman's book, Piloting, Seamanship and Small Boat Handling.
After a long Coast Guard career, I now make a few bucks consulting on boat accidents. Unfortunately, my continued employment is assured by people trying to cut corners by bypassing established procedures.