Not sure exactly what metric you are referring to for poor performance or in what conditions the mesh would achieve the poor performance you are referring to. As a former lead engineer on a mesh router system, I can assure you that mesh systems are capable of very high performance if done correctly and set up properly. Just about everyone uses them as far as I am aware. You wouldn't have one wireless access point for a whole massive building.
I thought wifi mesh systems were completely unthinkable in an enterprise environment considering their poor performance.
Not sure exactly what metric you are referring to for poor performance or in what conditions the mesh would achieve the poor performance you are referring to. As a former lead engineer on a mesh router system, I can assure you that mesh systems are capable of very high performance if done correctly and set up properly. Just about everyone uses them as far as I am aware. You wouldn't have one wireless access point for a whole massive building.
I’m imagining some kind of massive modified radio tower devoted to supplying wifi to a building directly below
No, you would use multiple access points, wired and likely powered with ethernet.