In Nick Layton's essay about phrasing he wrote that guitarists probably had the least developed skills in that area, and I think guitarists are probably the least developed in many other areas too, including practicing.
In my opinion, people who start learning guitar are often drawn in by the sense of freedom. No need for scale-practice and boring old teachers, just pick up yer axe and let rip! Many of our time's best known guitarists has had far from perfect technique.
But if/when you feel like seriously developing your technique, you find out that it takes a whole lot more than your usual jamhour/day to get where you want. I think it's here many are deterred because serious practice isn't for everybody. Even though you know your playing will improve drastically I think many people just don't think it's worth it since it can be easy to get bored when you go from just jamming freely to planning daily exercise routines.
Me I have never been able to plan my daily practice.
My first six months at the conservatory of music I tried doing everything right, warmup, lefthand exercises, right hand exercises, scales, arpeggios etc in that order.
Although I got better, I got bored. It simply wasn't that much fun to practice anymore.
I still loved playing guitar, but I wasn't looking forward to it as much as I used to.
So then I found something in between where I practice right, but only what I feel like and only when I feel like it. Some days I do my exercises and practice my new pieces for 6 hours, some days I play some cheesy Sonatine for 15 minutes and then I go home. It's all about having fun while you play. If you loose that you won't have much left.
Now don't get me wrong, I agree with your essay, what you say is very true.
Everyone serious about improving their technique should try those methods with the help of a good teacher.
Becoming a skilled guitarplayer is hard work, make no mistake about that, but if you hang in there and if you're having fun doing it, you're well on your way.
