My main question is why are hubs always half duplex and layer 2 switches can be full duplex?
Because let's say I have a ethernet cable that has pins that can send and receive data at the same time, and I use these cables to connect, let's say four devices, with a central hub in one place, and in another place I do the same thing in another location, but this time with a switch. Now in a scenario where all the devices are constantly sending broadcast messages, it does not matter if they are hubs or switches, they will all be flooded to all the ports. Now, in this case if a switch can be in full duplex, why can,t the hub as well?