Isn't part of the reason many people seem to have an issue with the idea of "yo-yoing" is that they are combining a narrative state into a mechanical one, and the narrative is what people have the issue with? That it's the idea of PCs "falling unconscious" then "waking up" then "falling unconscious again" then "waking up" again repeatedly that is the issue for a lot of folks? That it narratively just feels weird from a "what's happening in the world" standpoint, even though the mechanics turning "on and off" doesn't really matter?
Mechanically, when your "HP" score reaches 0, the following game mechanics happen to the character (taken from the "Unconscious", "Incapacitated" and "Prone" conditions:
- Character cannot take Actions or Reactions. ("Incapacitated")
- Character cannot Move ("Unconscious")
- Character's only option for movement is to Crawl ("Prone" - but whose rule gets overridden by the "Unconscious" condition)
- Character has Disadvantage on attack rolls ("Prone" - but whose rule gets overridden by the "Incapacitated" condition)
- STR and DEX saving throws are automatically failed. ("Unconscious")
- Attack rolls against the character have Advantage. ("Unconscious")
- Attack rolls from within 5' of the character have Advantage. ("Prone" - but whose rule gets overridden by the "Unconscious" condition)
- Attack rolls further than 5' from the character have Disadvantage. ("Prone")
- Any attack that hits the character from within 5' is automatically a Critical Hit. ("Unconscious")
- The character drops anything "in hand", is "incapable of speech", and is "unaware of its surroundings" (three narrative rather than mechanical abilities.)
While this is a lot of game mechanics that turn off and on when you go from 0 HP to positive HP... we players usually don't care when mechanics do. For instance when the "Prone" switch is thrown-- which means the character "cannot move except to Crawl or spend have your move value to Stand Up"-- we flip it on and off all the time throughout a combat and no one has an issue. A creature can "fall prone" and then "stand up" every round and it's just part of the mechanical combat-- heck, the new martial weapon abilities are giving the opportunity to throw the "prone" on and off switch more opportunities to be thrown than ever before.
So It seems to me the easiest way to "fix" the issue is to just change the narrative. If we remove the idea that a character "falls unconscious" when they mechanically reach 0 HP and get all those mechanics above turned off... and instead we just define them as being in some other state of being... moving them back and forth from that state of being and turning those mechanics on and off no longer becomes as much of an issue.
So for instance if we just called reaching 0 HP as "having your bell rung", or "stunned" or "overwhelmed" or "out of breath" or any other Thesaurus word you want to use... where narratively the character just has to pause a few moments to try and regain their senses while unable to do anything (can't move, can't act, can't react, doesn't want to speak, drops what it's holding, stops paying attention to what's happening around them)-- the idea of someone shaking them out of it (by giving them healing) but then they possibly return back to that state in a few moments when they lose it (if they go back to 0 HP)-- doesn't feel as weird.
I mean is it really that important that we have a state in the game when a character has completely blacked out? I don't think so. Blacking out is no better or worse a narrative state than just being out of breath or at a loss for words and action (stunned, dazed, the world goes fuzzy, however you wish to define it). So why be beholden to defining 0 HP that way? Just change how we view 0 HP and you don't have to worry about futzing with the mechanics (unless of course you like futzing with the mechanics, in which case have at it!)