L
lollipop
Guest
+1I notice asymmetry. I don't know if that would always cause strain or injury.
I think there is evidence of people doing well without pillows in various side-lying positions, too, so I'm guessing it's not so simple as that everybody needs to be supported in a straight spine position.
But if someone has an injury or pain, I certainly believe that supporting such a position could often be really helpful.
I think along with Peat's theory on life, it needs personal experimentation. I saw "the problems" so tried to mitigate for people. Might work perfectly fine for some as you mentioned.
One thing to notice, in experimenting, which position causes the neck and shoulder muscles to remain the softest and relaxed. That might correlate with more comfortable, and might not. Worth noticing.