Why do I hardly ever need Revivify or Withers?
Im asking myself the same question ... since there isnt even dificiulty there, we are playing the same game and i rarely use Withers, or Revivify scroll ... maybe you do something wrong? Just saying.
If I can use potions like candy and pop them as Bonus Actions every round, healing 2d4+2 or even 4d4+4 HP, AND I can have allies also throw additional potions to then increase my character's HP even higher, I could essentially restore a level 4 Fighter from 1 HP to 45 HP in one round if all four characters heal him/her.
I just love this theory every time you repeat it ... it never gets old.

All characters waste their actions (and one of them even Bonu action) to "keep your fighter alive and on full HP" ... while none enemy gets even single damage.

So ... you waste single turn ... Fighter is full ... so are enemies ...
You waste another turn ... Fighter is full ... so are enemies ...
You waste another turn ... Fighter is full ... so are enemies ...
You waste another turn ... Fighter is full ... so are enemies ...
And now you no longer have any potion left.
What exactly did you achieve by using this "incredibly OP mechanic" ?

I mean ... you can essentialy just destroy all your potions in first turn, and outcome will be the same, you just save some time.

Good question ...
Since you are the one who stated that you have the option, it would be great if you would answer it aswell.

If my fighter goes down, a single character can still use Help and bring him back immediately. Each round, he falls, and each round one of the party members just pops him right back up.
This "tactic" for lact of better therm is anyway only useable against single oponent.
Also do you find such game fun for you?
Bcs if not, you can proudly pat your shoulder that you exploited through combat encounter, but you essentialy achieved nothing.

As a side note: drinking potion as a bonus action is one of the most popular homebrew I have encountered in 5e. Just saying.
Agreed +1!
This is one of things that should never change!