Pain and Ashtanga....once again, these two words end up in a sentence. I am not even going to site the articles and teachers who have reawakened this sleeping demon. Lets just say, they are on the side of pain.
I am not totally against pain. In some instances, rehabilitation can be painful. Many people use their yoga practice as physical therapy for previous injuries and health conditions. Strengthening, stretching, breaking up scar tissue and reestablishing full range of motion so that a muscle can heal properly can be painful. That is pretty much the only time when pain can be an acceptable part of practice. When speaking to my students on pain, I give them advice and options and I let them know that I am not a doctor and leave it up to them as to how they want to proceed and I support whatever decision they make.
There are two things that concern me when talking about yoga and pain. The audience and the normalization of pain. Who knows who is reading these blog posts and watching these YouTube videos?! It is one thing to write a blog talking about your personal experiences with pain but giving advice on pain to complete strangers is another. Writing an article saying that pain is good, that is going out to God knows who to use as they see fit without even a disclaimer or indepth explanation, is careless and irresponsible.
I also have a problem with Ashtangi's who normalize pain and teach that it is a part of the practice. Pain does not need to be apart of the practice. If it is, then you deal with it, but searching for it and purposely trying to bring it on because it may help you get deeper into a pose is not yoga.
One of the basic tenets of yoga, as mentioned in the Yoga Sutras of Patanjali (you can call it the Bible of modern yoga) states that yogis should practice Ahimsa, or non harming. Pain is a sign that our bodies have been harmed. If pain comes up during practice or is a result of practice, the yogi figures out a way to intelligently deal with it but they don't purposely create it.