Balance

The Impossible only works if no one believes anyone could do it.

The idea of balance in a RPG setting arguably comes from the influence of video games and similar media.

Instead of thinking encounters as a matter of balance thinking of an encounter as a real world

Then thinking about balance and how as a game these choices can create challenges and drama can lead to some of the best encounters you could have never planned because you and your players would never had thought it would of worked. That fine line between what would of happened because the world is a real place and the fact that your players are the main characters of this story and how they overcome the impossible is what makes great stories. It is a line that is very tricky to balance and in trying it can easily become a question of every single encounter becoming a slog of deadly enemies and tarpit hordes but when using sparingly or as more often when the players have already thought that this miniboss is a caster and already are dealing with that danger who is anyone to take that heroic moment away from them because a goblin chief who is a level X caster wouldn’t be balanced?

Example: in Red Hand of Doom the players have to cross and destroy a bridge guarded by Hobgoblins and a Youngish Green Dragon (At 5-6 level).

Giving the players the impossible challenge they found a work around the monk jumped onto the Dragon as it swiped at him, tied a rope around part of the pillar of the bridge and tied the other end to the Dragons talon before stunning striking and jumping off. The Dragon and bridge take massive amounts of damage from the fall and weight of the Dragon respectively.

Alternatively the Dragon plays it safe and we enter a grind fest of trying to get it to fly down. By instead holding the Dragon back and allowing the players to take one side of the bridge the scale grew as what could have been two or three encounters were three stages of a rolling boss battle that everyone remembered.

Adventure League is a great example end of module usually has a mini or less than miniature boss and if this was a fair and balanced war game then yes the mini boss would spaff its collective spell slots at the squishy and step on their head to make sure they are dead. Happily this is not a war game, they are probably more concerned with the five other adventures intent on ending their dance upon the mortal plain and they may not know who is squishy or worse if there is another crew of adventures on their way.   

Balance is already on the players side, the bad guys life is measured in rounds and spell slots. The baddie using their abilities increasingly frenzied and realising the players are a threat is what makes them memorable, the cleric having to roll an 8 on a D8 to not die is memorable. The underpowered demon who has been living as a Dwarf lord for 50 years isn’t. That being said as always if overused it can be damaging even frustrating but being mindful of the balance and why you are running the encounter the way you are is an important tool in seeing where you can improve and what your players respond to.

Arguably of course.