If you ask wheelchair users about belts or other postural supports, quite often you'll hear answers like, "I don't want to be belted into a chair." This can be the case even when someone is clearly in pain or an uncomfortable position.
RESNA, the organization that certifies assistive technology professionals (ATPs) in the US, published a position paper that includes a list of what therapists see as reasons for postural support beyond the chair itself. These include support against gravity, voluntary or involuntary movement, that increases the risk of pressure ulcers, pain or deformity.
Other reasons that the paper provides include maintenance of postures that improve function or health, including stabilizing one part of the body so another part can do more.
The takeaway: all of these reasons increase function, comfort and safety -- exactly so a body can do more than be "belted in."
If someone's entire torso is twisted or slumped, a single pelvic belt won't change that. But with the right combination of other supports, we can change lives.
Don't let myths scare you away from the comfort and function that you or someone you know deserves.