Jumping back into the discussion. Tatum as the top dog, the alpha, the Batman, is not in my view up there with Jordan or Magic or Bird or LeBron or others of that tier. But he is in that next tier in my view with championship players such as Leonard, Curry, Duncan, Pierce/Garnet, and some others. So in my mind, whether he is or will be top 30 all time or top 40 all time or top 50 all time, is not the point. To me, he is good enough to win a title if a good enough team is put around him. All these players needed a good team around them.
Then consider Brown as compared to the #2s these other top players had. Magic had Kareem, tough to top that. But is Pippen better than Brown? How about McHale? Siakam was the #2 for Leonard. Tony Parker for Duncan. Klay Thompson for Curry. Brown to me is better than the majority of these other #2s.
Tatum+Brown is as good as any of these 1-2 with the exception of Magic+Kareem. You could argue that because Jordan is much better than Tatum, that Jordan+Pippen is better. But Tatum+Brown holds up just fine against most of these 1+2 champions.