the important point here is not who is right or wrong,.
If when you start playing you learn good technique,you are not limiting yourself, if later in life, you wish to change direction and play classical music, or jazz or scott skinner compositions[which requires going into different positions].
I know several musicians for example,Ed Caines ,Cathy Cook, Tom mconville who started playing classical music,but who make a good job of playing traditional music, but still have good technique,both of these musicians have played successfully for traditional dance.
and could if they so wished play classical music successfully.
however if you learn bad technique[ supporting the instrument with your arm][[ incorrect bow hold]]you may be able to play much of the traditional repertoire successfully,but be even limited within this sphere[tunes like The Dawn,Scott Skinner compositions,sean sa cheo etc,
Being able to change position has advantages in traditional music as well, for instance it is easier to play a G roll or an A roll [on the d string,using the stronger fingers,index and middle,than using the third or fourth fingers,this is done by changing position.in fact it is impossible to play an a roll abaga,on the open A string,You have to do a treble or a trill or a cut or a double cut or a fake roll,the musician who has good technique has more options.
    on any instrument good technique is important,but technique is only one factor, playing in a musical way, use of dynamics ,being able to express feeling,particuarly on airs[good technique is important here]are equally important.
classical musicians can learn to play traditional music successfully if they listen to the music for long enough,and absorb the styles .
but musicians who hold the violin /fiddle incorrectly will find their musical horizons limited and there will be even a few limitations within the traditional repertoire.

I disagree with some of your esteemed colleagues comments in his article,good technique on any instrument is important although technique in itself is useless unless the musician is musical,at the same time, good music can be made with limited technique,but the musician will always be limited with what he can acheieve,which becomes frustrating for the musician concerned.