Sounds like a poorly written article to explain a really basic strength development principle. By holding the heavier weight, you can actually improve trunk strength and stability in prepraration for the heavier lifts. You can do the same thing with upper body presses as the big limiter is shoulder stability. This is called "static overload".
Strongman competitors do some work like this... Here are two techniques that I actually employ:
One drill I used to do when I actually cared about how much I could squat was purely psychological. I could not get past that 400 pound barrier. Part of the problem was that mentally, when I would feel that weight on my neck, is that I got psyched out... it felt like I could never go down and come back up with it. But, according to my projected max from what I was repping with, I should have been able to do it. I would load the bar up with over 500 pounds, unrack it, stand in position, and just stand there for a minute. It felt REALLY heavy! Then, my partner and I would strip the bar very quickly to 405, and I would unrack it. It felt so much lighter than what I had on that eventually I defeated my own mental barrier, and one day felt like I could come back up with it, so I did.
Another drill is the Farmers Walk! Farmers walk will absolutely demolish your forearms, upper arms, and traps, as well as building those trunk stabalizers. It is one of the best exercises out there. Very simple... Just grab a couple of hundred lb. dumbbells and walk with them. Give yourself a goal destination and try to walk there and back to the rack without setting the weights down.
Here's Strongman Competitor Chad Coy doing the Farmer's Walk with 330 pounds in each hand.