I would never want to assume that just because I can long arm doesn't mean that I would stand a better chance of being accepted into a show.
You know, many of the extremely heavily quilted show quilts are not done on longarms, but are done on full size domestics (as opposed to the 3/4 size machines many occasional sewers have.) Then a number are done on large harp space domestics, which are still fairly affordable compared to long arms.
And of those long armed, very few show quilts are computer quilted. Computer quilting is actually more common for home use quilts, because it is fast and efficient. Custom quilting is generally hand guided.