I was having debate with one of my players about a possible upcoming scenario and I would love some input. He is a multi-classed Sorcerer/Warlock and at some point soon hopes to use the darkness/Devil's Sight combo. The party also includes a Ranger/Rogue multi-class and she makes great use of her Sneak Attack.

Now I understand that if all creatures, both friendly and hostile, are in darkness then all advantage from unseen attacks and disadvantage from being the target of an unseen attacker cancel out, creating a level playing field (a bunch of people blindfolded with sticks have an equal opportunity to hit one another.)

The issue I'm running into is this: Is the Rogue able to use her Sneak Attack even though she is in darkness?

My initial thought was no, because even though according to the RAW it's a level playing field and she should still be able to do things like do an extra 1d6 damage on an attack if the hostile creature is within 5 feet of her allies etc.; thematically I'm hitting a wall because it's a skill that assumes the creature (let's say a bugbear) is being distracted by an ally (let's say our Dwarf Paladin) so the rogue takes advantage of that distraction and zeros in on a vulnerable spot and gains the extra 1d6 of damage.

But in darkness, the bugbear can't see the Paladin to be distracted or engaged in the same way he could in light, and the rogue can't study the bugbear in darkness and is essentially using her hearing and firing a shot into the dark. So it makes little sense to me to allow the use of certain skills that rely on such thematic precision even though total darkness for all creates a level playing field (except for the Devil's-Sighted Sorlock who is running around wreaking havoc).

In this scenario, the only player with Devil's Sight would be the Sorcerer/Warlock. The other three players (Rogue/Ranger, Paladin, Bard) would not have vision in darkness and while it is a useful strategy for the Sorlock, he has concerns that it would nerf the other players' abilities and we wanted to get a clear answer before this scenario presents itself.

I do know that as DM I can rule one way or the other but, as cheesy as it sounds, I like to create a game where all the players feel a sense of ownership and agency in the world and would rather not slam down an iron monarchical fist and instead get input and make a decision. I should say that I do value thematically believable RP in my games fairly high.

By RAW, the rogue can sneak attack as long as the target has an enemy within 5 ft of it

From the Rogue's Sneak attack:

You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll.

and from the Basic Rules(Emphasis Mine)

If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage.

Because both the rogue and the target are blinded, the advantage and disadvantage cancel each other out, and the rogue is determined to have neither. Thus, as the target has an enemy within 5 ft of it, the rogue may apply their sneak attack.

In terms of the fiction, I personally think of this as the target stumbling around in the dark looking for the rogue's ally, when suddenly they get blindsided by the rogue.