This question is asked a lot by those people with low back pain, especially those who do manual work. In some times of back pain the entire muscle group of the low back goes into a kind of protective and panicky spasm.
It is true that for these kinds of patients the sense of compressive support that they get from the back support device does seem to 'calm' the muscles and, as a result, they feel less uncomfortable and often able to move around more.
The problem occurs when the back support device is used too much. Beyond a certain point the benefits get outweighed by the growing penalty of the muscles getting more and more lazy and confused.
Its a difficult balance to strike; use them - but not too much.