It's a very interesting article and I do use it myself, as a violin teacher, to explain to students more about bowing and tone (if they are interested).
It busts the myth about the 'silent bow changes', which are physically impossible as the Helmholtz movement simply has to be stopped and go the other direction.
However very interesting, it does not point out the nr 1 reason why violin playing is so hard...
My students most of the time have a decent basic (!) bowing technique and tone in a couple of lessons. Of course they don't have a professional tone and are not able of more advanced bowing techniques at this point.
The real trouble starts with intonation (playing in tune) and as violinists we can't use frets as the intonation needs to be flexible depending if we play in a certain key, where the melody goes, what the harmonic function is and if we play with an orchestra, pianist or string quartet. All this while learning a 'whole tempered' tuning on the violin is already difficult enough as it is.
Besides that what a lot of students find hard is the multitasking... difficult bowing technique, reading notes, watching a conductor or other players, intonation, rhythm, expression and interpretation and all the other stuff that musicians in general cope with while playing.
Of course every instrument on a high level is difficult. Everybody and monkeys can hit some random keys on a piano and sound in tune with a decent tone, but to play Chopin is a whole different story.
What makes the piano more accessible is that with a little to no basic technique one could still play a simple nice sounding song. Besides that on a piano or guitar one could play a couple of chords and sound good already. However, I hear a lot of piano students hit a 'plateau' after some years and not much of them can go beyond this. It takes a lot of practice hours and good teaching to beat this plateau and get to an advanced level.
With the violin all difficulties are there right in the beginning and for many it takes years to play something that doesn't make people want to put cotton in their ears ;). Let's say the plateau that appears for pianists after some years, is there for the violin right in the beginning.
Al this being said (and I hope I haven't bored you), playing a musical instrument is a learnable skill. There is input (good lessons, practice hours) and a predictable output (play beautifully). Of course to achieve a soloist/prodigy/alien level, a little talent might certainly help.
All the best,
Zlata Brouwer, online violin teacher