It must be true. It's on the Internet.
The pads tune the panels so they don't resonate at typical speeds and use conditions. Some is caused by driveline vibration, some by wind loads, and the exhaust system can also contribute.
You don't need to coat a tuning fork with rubber to keep it from vibrating. A little dab of chewing gum will do it.
I've purchased nearly 180 sf of sound/temp insulation, Ford gives you enough to dampen the noise to a reasonable level, I'd guess 70-something dB at highway speeds. Good enough for most.