The report comes from some Apple employee training documents acquired by MacRumors. The documents state that Apple employees "will not size links or swap band". The appointments are only meant to last about 5-15 minutes so Apple is looking to save time.
All is not lost for folks wanting to change out the stock watchband. Apparently Apple will have 18 different Apple Watch combinations at Try-On tables and 10 combinations at their cases. Apple Watch pre-sales begin on April 10.