Knowing what good technique is is a bit of a red herring I think--the bugbear of people who aren't that good yet, or the recently-good. I say this because I used to watch out for examples of poor guitar technique and be sort of critical of them but in doing so I noticed something--the moment poor technique got in the way of what they were doing they stopped doing it. Immediately, mid tune, no problem. I've seen this countless times--you can watch someone go from having their thumb on the top of the neck and their pinky on the soundboard and all sorts of little deficiencies and just watch each of them drop away and come back as the music requires it. This kind of malleability in the moment is the common element in the best musicians I think. As a matter of practice you'll certainly waste less time if someone points out poor technique early for you, but beyond the edge cases where poor technique is injurious that's about it (and I'd note, the vast majority of steel string guitar finger-style playing is of the injurious sort, but its just rarely played long and vigorously enough to become so). On the other hand, read this interview with Keith Frazer [1], whose slavish devotion to proper technique has left him irreparably damaged.
The fact is, at a certain level of playing, you stop asking "is this correct technique?" and you start asking, "does this make the music I am playing better? am i bringing attention to what i want to bring out of the piece? does it make it easier to play?" Preoccupation with correct technique as a separate existing thing from external authority becomes a hindrance. You want to learn about your art from those around you, and have them learn from you. If you don't feel ready or capable of being independent in this regard, that's fine. But not everyone is an amateur, and no one claims to ever stop learning, so what are they doing differently?
e: What most interests me about the article is that this comment section is filled entirely with people, like myself, who's opinion on the matter has not been changed one iota by the article
[1] http://www.keithfrazer.com/interview.htm