It's no secret that shame is a part of social anxiety...our fear of being judged by others in a negative way is the crux of our problem.
But to say that shame is the cause of our conditions is not exactly true. Shame is an emotion, a mental state, that results from the way we interact with society.
I think the "toxic shame" theory confuses a symptom for the "disease" itself.
But I do hear what you are saying about acceptance...that is an extremely important part of getting better. If you look a lot of validated therapies like Mindfulness Based Cognitive Therapy and Acceptance & Commitment Therapy employ acceptance of your thoughts and yourself as a person.