The rules of competition fishing are intriguing, with many rules probably born from where someone gained an advantage. Competition rules Loch Style excludes dapping, mainly on fly size, but also in the interpretation of what is/is not a fly line and what is/is not running/shooting line. Rod length is a thing, but I have used rods of 12' or less to dap - albeit its not an optimal approach, it works.
IMHO 'loch style' is not so much about the traditions or tactics directly associated with the approach we might take to a days loch fishing but more a derivative of one particular facet of the sport into a competitive clique.