Broadcast and security issues related to ARP can be mitigated with modern switches. Cisco switches support several security technologies specifically designed to mitigate Ethernet issues related to broadcasts, in general, and ARP, in particular.
Switches provide segmentation of a LAN, dividing the LAN into independent collision domains. Each port on a switch represents a separate collision domain and provides the full media bandwidth to the node or nodes connected on that port. While switches do not by default prevent broadcasts from propagating to connected devices, they do isolate unicast Ethernet communications so that they are only "heard" by the source and destination devices. So if there are a large number of ARP requests, each ARP reply will only be between two devices.
With regard to mitigating various types of broadcast attacks, to which Ethernet networks are prone, network engineers implement Cisco switch security technologies such as specialized access lists and port security.