Assume that the rating of your boat (and the rating for your opponent) are just 2% off the "correct" values for that day and race course (and this is VERY optimistic for the simplistic formulas used in schrs or texel). This corresponds to an error of about 100 seconds for a 1 hour race. In one design you usually see quite a few boats crossing the finish line within 100 seconds (almost 2 minutes). In one desgin these boats have a well established order, in races with rating they don't. Of course, the good sailors will beat the bad ones, but it makes no sense in establishing an order by comparing corrected times that are within these error limits.