I would agree with this.
It really depends what your goals are though.
I have to say I can see where you guys are coming from in terms of skill specific training, but at the same time, I hope you can benefit from my personal experience with oly lifting.
Four years back I had all sorts of mobility and strength issues and while my primary goal was to be good at parkour (which I still am not), I decided that a more structured approach to my training would be required or my current limitations would cause me to shy away from it altogether.
I think skill based training will teach you to maximize your current strength and power levels, IF you haven't already, and that's the key. IF you haven't, it will give you the most bang for your buck in the very early stages of your training, but once you've done that, you're going to want to have a foundation to fall back on in order to continue to progress
Back to my personal experience, I took the Vertical test recommended on this site, where you jump up and paste a piece of tape to mark your highest leap, and pretty much forgot about it while I focused heavily on oly lifting... well, on my own version of CrossFit that required more and heavier oly lifts in the workouts, and pretty much came back to the vertical a few months later, solely for the purpose of pointing out to a friend what "vertical" meant.
I was pleasantly surprised to see that not only did my vertical gain a full foot, but somehow, I knew it had... I knew how high I could jump and what I could reach... Was the combination of oly + parkour stressful on my knees? Not really, but you can argue I wasn't doing a ton of parkour anyway.
I have since deviated from oly lifts in favor of more power lifting, and have consequently noted mild regressions in terms of both the vertical and the broach jump, but I suspect I will be quickly regaining those few inches (and then some) as I resume more skill based, and yes, more power based training (in the form of oly lifts)
Now, full disclosure, I'm going to be 40 in the next couple of months, and I weigh about 205 lbs. You can argue that, 4 years ago (at 235# with chicken legs and huge mobility challenges), to think I was going to have a 9' or 10' broad jump without some massive strength gains (and some weight loss), would have been laughable, so I made a choice that was clear to me given the circumstances I was presented with at the time.
The point I'm trying to make is, take a look in the mirror, in a matter of speaking, see where you are at, and what will get you where you want to be. If you think you have enough leg strength to propel you those few extra inches, and you think those few will be enough, then focus on skill and skill alone. If you, like me, know that once you get those inches you're only going to want more, start building strength and power now, don't wait until you've maximized the benefits of skill based training.