Actually it was never a myth, look back to the B5 RS4 it was the only RS car, then it was the C5 RS6 and then the B7 RS4 and then the C6 RS6. Typically the RS models only came out when a platform was 2 years from the end of it’s life.
Audi realized that customer wanted more hi powered cars and BMW with the M division and Merc with AMG were making a killing, with Audi wanting to be the most dominant luxury car manufacturer they had to do something about it - hence why the 1 RS model has gone out the window in the last couple of years and there has been an influx of them and it is also the reason why Audi is striving to have something like 28 different body styles on the market by 2015 (could be wrong on the year, but it is somewhere around there)