There is a tips page in-game, if you go to options in the character select menu! It's also mentioned in the game's description. But you're right, 90% of players missed it so I should make it more obvious.
It's weird, when i tried this mechanic it never worked for me. Maybe it's my keyboard.
Also i don't like how it is now becuase it punish you for near misses. Like you can have 2 life and no stamina and you can still have a short recovery. Or the contrary being full and have a long recovery. Sometimes i prefer that they just stomp me once well early on because i could just heal myself while i can't heal my near miss. So in the final stage i still have fast recovery.
Also i will prefer instead of smashing a button. I prefer a timed minigame where you press in the center of a bar and it gets smaller the more screwed you are