I’d say random rolling an encounter is the opposite of choice. It’s representing the variance of the fantasy world: if there’s a 1% chance of someone traveling through a given region encountering a dragon, rolling a 100 on a d100 table emulates that.

Imagine that a DM decided to prescript combat so that every player gets down low HP before the enemy dies in the fourth round. The DM doesn’t give the enemy HP, they pretend to roll behind the screen, and they mete out damage at predetermined intervals. This happens regardless of whether:

• The rogue decides to use their inspiration after a miss to try for sneak attack
• The wizard uses Fireball for damage, tries to break concentration with Magic Missile, tried to Hold Person the enemy, or just cast Firebolt
• The Eldritch knight uses Shield to absorb a hit
• The cleric buffs and heals the party vs. focuses on damage
• The barbarian uses rage or saves it forever
• Which wild shape the druid chooses

Regardless of any of these decisions, the DM has already planned the entire thing out. Attacks hit when the DM wants them to hit, the DM makes up that the enemy is “starting to look bad” when they’re not tracking HP at all, the enemy suddenly saves against things that would be encounter-ending, etc. This is basically the quantum ogre.

Rolling in the open, letting hits hit and misses miss, suddenly makes those decisions important, because the DM can’t just lie to meet a predetermined outcome. Rollable tables are a similar sort of randomness that discourage a DM from just forcing a predetermined outcome at the player. A random generator is not even a choice at all: other than choosing when to roll it, the DM has no influence over the result.

I see the QO as a stepping stone to using random encounters, and to prepping enemy stats but not setting the encounter itself in stone.