Is rogue a single or multi/dip into class?

[RogueJK]

Battle Master 5 is roughly +54

DPR is not the be-all and end-all of combat. A Battlemaster is not only adding damage, but has the ability to add other effects as well, which aren't quantified in DPR calculations. (That would be part of the "and more" to which I alluded.)

You're also not factoring in the Battlemaster's ability to Riposte, which is one of the few ways that Rogues can potentially get two Sneak Attacks per round. (Once on their turn, and once on the enemy's turn with a successful Riposte.) That would boost the DPR numbers further.

Str is not alien to Rogue. Cunning Action: Hide is the only feature strongly tied to Dex.

There's already a huge incentive for Rogues to focus on DEX, by necessitating the use of Finesse or Ranged weapons for Sneak Attack. There's no benefit there for going STR over DEX, since you can't use bigger weapons.

And the Rogue's other out of combat skills/roles, namely that of the Stealthy Scout, Trap Disarmer, Lock Picker, etc. would all suffer by having a lower DEX. Plus the likely need to invest in Medium/Heavy Armor to offset your lower DEX, which would further dampen Stealth. (This hurts certain subclasses like Assassin even more than others.)

I'm not saying that you can't make a STR Rogue, only that making a STR Rogue has some noticeable drawbacks compared to the traditional DEX Rogue. Again, a STR-focus runs counter to the Rogue's strengths, just like the Barbarian's class abilities, while mixing in some Fighter/Ranger levels affords additional abilities that complement and reinforce the DEX-based Rogue's existing strengths.