I wish I could find someone to tour with who subscribed to that theory, I'd gladly let them take my luggage! I haven't clicked the link, I don't need to, the only way to reach such a conclusion is to disregard acceleration. Yes, bobbing along on the flat and an extra 5kg won't be noticed, but every time you slow or stop, any extra weight requires a proportional increase in energy to get it back up to speed, whether you notice it or not...
That why I said "In theory" as I'm not convinced by that theory. It clearly requires extra effort to get more weight up a hill which might not matter much if that effort is rewarded by cruising downhill and then half way up the next one (on open roads I found those with lighter bikes seemed to go down hills more slowly than my Mercury). However, where going down requires generous use of brakes then all that effort is wasted. That said, I'm struggling to think of what I could leave off my Mercury in order to shed weight. I could take a chance with lighter tyres and remove the frame lock as the bike isn't left unattended.
I took a close look at the front wheel today and the cause of the warp was quickly identified: One broken nipple. I was surprised how much deformation resulted from this. The bike came with some spare spokes and nipples so I used one of those for the repair and have got the wheel back into acceptable shape (my tolerance about 1/2mm) using eyeball and a 6" ruler taped to the forks.
