In a vacuum, most of that might be right. But here's the rest of the story.
In Zealots he can start 5 RBs and he's pretty loaded there with Chubb/Elliot/Henry/DJohnson/Lindsay.
But then he can only start 2 WRs. And his top scorer from last year is Calvin Ridley. So he loses a ton of points from those two slots.
As to the QBs, he started Luck twice and Watson ZERO. The rest went to Mahomes. And they will for the far future.
So Luck & Watson only have potential, not actual, value to him. New team or no, Brown is a huge upgrade for him at the WR position. If he can acquire it for the cost of a rookie and a guy he knows he's going to most likely get a zero from otherwise, it only makes sense to work on something he can agree on.
Otherwise, he can be an middling team that can take comfort in knowing he had Luck and/or Watson on his roster for a decade - and got backup points from them.