The properties of the devices they use for managing nasties have to match the application. They can't use the same MOVs for Ethernet for example as for POTS. The MOVs have parasitic capacitance that can attenuate the Ethernet signal. It's quite challenging actually to provide cost-effective, space-conscious, low let-through protection for high speed signals.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated