So... is the actual problem being addressed really 'yo-yo healing', or is it the game not being lethal enough? Because most of the solutions are 'make the game more lethal' and if that's not the intent, it's just punishing players for a game design decision.
Killing them for going down (when in-combat healing cannot possibly prevent it), imposing penalties that ensure they'll be doing down again soon, making it more likely they'll die if they go down again--none of it actually fixes the issue of people coming back up from 0, it just tacks on an all new, all different problem.
Punishing people to discourage a problem doesn't solve the problem is it's not one the punished person can't control.
I'm taking 30 points of damage a round and the cleric is on a bad roll and giving me 12 back, it doesn't matter if I see the DM cutting a hickory switch and taking practice swings on the other side of the table, I'm going to go down to zero, either because the DM miscalculated (or worse used CR) or because the expected heals aren't keeping up with damage output--neither of which is my fault, but I'm the one about to have a sore red bum for some reason? That doesn't seem right.