I feel a disconnect on how the term "deep tissue" is defined by clients and therapists. I don't think therapists have done enough to clarify the term for the non practitioner. Many clients think that deep tissue and heavy pressure are synonymous but that is not always the case.
"Deep tissue" refers to the layers of muscle that lie beneath surface muscles close to the bone. To access that layer of tissue one must first make the surface muscles warm and pliable. Heavy pressure is harmful if applied too soon causing the surface muscle to brace in defense. Not every body needs every muscle to be stripped to the bone in every massage.
An entire science has been devoted to relief employing sublte methods that target and eliminate the cause of the pain. Therefore it could be that the most effective therapists dont need to employ tons of pressure. Pain relief doesn't have to be painful!