why does tryndamere's spin cancel prior movement unlike most other dashes in the game?

step 1: be a character with a dash step 2: move somewhere step 3: quick cast the button to dash step 4: after it ends your character will continue walking towards the location you clicked in step 2 step 5: this does not work with tryndamere, which is inconvenient if you want to tap the E key while trying to get into lane faster for example.