From the article:

"A recent survey of more than 700 hip and knee surgeons confirmed Dr. Yates’s impressions. Sixty-two percent said they used body mass index scores as cutoffs for requiring weight loss before offering surgery."

It sounds to me like "cutoffs" and "requiring" would indicate a blanket refusal, and 62% seems like a fairly large scale to me. What evidence are you looking for?

Other common conditions can also increase risks of complications, and patients are routinely given opportunities to weigh those risks before deciding on surgeries. My suggestion isn't that the doctor throw his duties out the window, but that with high-BMI patients, those duties should not suddenly become more dictatorial than with other patients.

There's a difference between saying "You're fat, so we won't operate on you." versus "The pain that you hope to fix will become worse if we perform surgery on you." Surgeries that involve weight-bearing joints and bones are particularly sensitive to the mass of the patient (like the hip and knee surgeons surveyed). For heavier patients, the healing time is longer and the risk of additional pain after surgery is much much higher.

Some aren't. Patients with severe hypertension, for instance, are often categorically denied non-critical surgeries as well.