Well I guess 'the right way' is that which accomplishes your aim as efficiently as possible with a minimum risk of injury. There will always be more in common than different in the ways people lift anything. Also, I think strongman lifts have accepted techniques just like the olympic lifts. Take the stones: there is pretty much a consensus on how the lift should be performed. Try and do something wildly different and you'll probably fail.
These things which all the movements have in common is the most important factor. Take for example keeping a straight back and bracing your spine. This is pretty fundamental to any lift you like. This can be learnt in various ways; however, the end result is the same. I learnt it doing heavy deadlifts. Now I know what to do when I'm asked to snatch or load a heavy sandbag. The basics stay the same regardless of the object being lifted. I would argue that this understanding, this proprioceptive knowledge and body coordination, is just as important as sheer loading.
Getting into the specifics of the knee rebend, well this couldn't be more natural in my opinion. Take anyone untrained or trained and get them to pick something heavy up to the shoulder. Alternatively, get them to lean forward at the waist, then tell them to jump as high as possible. I really didn't understand the idea of the rebend till I started olympic lifting, but if you think about it, it makes perfect sense. Let me throw one back at you: look at stone lifting. You have a first pull to get it past the knees. Then the knees rebend, albeit to a much greater extent than in an olympic 2nd pull, and the stone is rolled onto the thighs and lapped. From them comes explosive hip AND knee extension to load the stone. To my eyes, this is pretty similar to an olympic lift. The differences are semantics when you get down to it.
We want a lift that teaches us to perform this movement in as biomechanically sound a way as possible. Thus when the body is asked to do something similar on the sports field, it will get pretty close to the ideal. This, for me, is strength. Strength, after all, is no more than another skill. You get better at it by practising it. It involves learning greater recruitment of muscle fibres. This is just like learning the piano, just gross motor rather than fine. Moving better makes you stronger, therefore.