“Can’t” or “Won’t”? It’s still the farming example. Hire the farming expert to grow what you want (catching coach and drafted prospects), trade for prospects with some development already done, or sign free agents, or choose to be bad at the position.
Today they can trade Vázquez, but it would be choosing to be a worse team.
they can poach Tanner Swanson from Ny or hire another catching whisperer, and spend more draft capital on Catchers
there is no salary cap, they can spend whatever they want. They could have signed d’Arnaud for the same money they paid Bader.