To add to the HJ/MD blunder, the first iteration's problem wasn't just "because people mashed too much" if you so much as tapped the button twice or your keyboard sent 2 tiny repeated keystrokes it would send the locked queue with HJ and MD, and ruin your pull in record time.
Having to very delicately press a button that must always be used on CD no matter what was just straight up AWFUL and made the job feel like you were jumping around eggshells to not self-sabotage.

The second iteration added a cooldown to MD to prevent accidental queuing, so now unless you had 40 ping or something incredibly low double weaving HJ and MD was impossible without clipping and even if you lived next to the server it ruined a lot of fights tight MD usage during time limited phases because it was now simply impossible to fit MD.