Do supertweeters matter when we cant hear past 15,000 hz?

So I have read that studies of the brain have shown that frequencies above audible are still somehow processed and generate a sense of ease, well being when associated with musical playback. As in somehow the range far above hearing is stimulating a  part of our brain, (or god knows what nuerons) that associates with a natural pleasing sound. Anybody read of this phenomenom? I see some of these supertweters extending to ridiculous highs and wonder if they do this just becauser the design allows for it or are they trying to market this broad range as somehow better. I know I cant hear above 15khz and i doubt most men here above 40 can either. I know a supertweeter helps with the audible high end but what gives with promoting a range to 65kz?