This is JUST my opinion. I am not going to claim I am right, but I will say it is what I believe to be true.
IMO, nock pinch matters if WE do it, as when we do it we put pressure on the arrow in a way that we torque a shaft. A pinch on the nock though caused by nocking points (especially tie on ones), isn't going to matter since it only pinches the plastic nock...and would do so in an evenly distributed manner and therefore would not torque the shaft. All that pinch does is "lock" the arrow into position...and by the time the arrow approaches brace that "lock" is of course released. With metal nocks I would be more concerned about it as metal may crush the plastic nocks and may perhaps crack them. Additionally, if the archer shoots split finger, they do hold the string open somewhat.
That said, I myself only use one nocking point on my bow; however, I have my kid's bows set up with double nocking points so they don't accidentally move their arrow down. When I tie on the second nocking point, I put a spare nock on the string and tie to fit...not tight or squeezing, but just to barely contact it. Once I am finished, I watch them shoot to check for proper arrow flight...and adjust it if necessary.
These shots are live on the video above.