This is where disagreement exists.

Bud-- wrote:
A MOV clamps the voltage across its terminals. Surge supressors
fundamentally clamp the voltages on the protected wires to a common
reference point. We both agree the ground path fom an receptacle to the
power service panel is relatively high resistance. The protection
provided by plug-in surge supressors is primarily by clamping, the
conduction to earth is secondary. In the fig 8/fig 9 TV example, most of
the earthing of the surge on the CATV service is via the "Coax sheath
ground bond" from the CATV entrance ground block to the power service
entrance (IIRC the paper says that).

Bud describes differential mode protection. Destructive transients
are common mode. Yes a MOV can clamp (short circuit) a voltage between
two wires. And that transient is typically not destructive.
Differential mode transients are not typically sourced by lightning.
Typically destructive transient is common mode. Clamping between two
wires only puts that common mode transient on both wires - and still
seeking earth ground.

Defined previously were two computers connected to plug-in protectors
and powered off. A destructive transient was clamped by MOVs inside
adjacent protectors. Now that destructive transient has more paths
into the adjacent computer. That transient took paths provided by
clamping in an adjacent protector. Incoming on AC wire. Outgoing on
network. Down network wire to a third computer. Out that third
computer via a modem and phone line to earth ground. Each damaged IC
in that path was replaced; computers worked again.

Adjacent protectors did clamp the transient. Transient was clamped
right into a destructive path through computers. Telephone switching
centers don't put protectors adjacent to electronics for same reasons.
Telco prefers shunt mode protectors to be up to 50 meters away from
electronics - and short distance to earth. Why? As demonstrated
above, clamping adjacent to electronics can even contribute to
electronic damage. Clamping at the earth ground shunts (diverts,
connects, intercepts) a destructive transient to earth long before it
can find earthing paths destructively through electronics.

Fig 8/9 TV example demonstrates but another 'sneak' path that
contributes to damage. Why. Clamping was too close to electronics and
too far from earth ground. Rooms are constructed with 'sneak' paths
everywhere. Just another reason why clamping must be at the earthing
connection. That IEEE paper (previously attributed to Mike Holt)
demonstrates too many ways for a plug-in (point of use) protector to
fail; even contribute to electronics damage.

Shunt mode protectors are effective when shunting (clamping) short to
earth ground. Plug-in protectors (also called shunt mode devices) hope
you never learn about the typically destructive transient AND why
shunting must be both short to earth and distant from electronics.

Bud is describing protection from a transient that typically does not
do damage AND that is made irrelevant by protection already inside all
electronics.

Why is the 'whole house' protector so effective? 1) It shunts or
clamps all types of transients. It does that clamping distant from
electronics. 2) It does that clamping short to earth. It is properly
sized. 3) It connects to what shunt mode protectors need to be
effective: single point earth ground. Not just any ground. A short
connection to single point earthing. Clamping is ineffective if no
earthing to clamp to. Earthing that provides both equipotential and
conductivity. And yes, both conductivity and equipotential are
necessary for shunt mode devices to be effective. MOV not clamping to
earth (above example) even contributed to damage of three networked
computers. I have seen such damage too often to believe plug-in
protectors are worth ten times more money per protected appliance.

Why are 'whole house' protectors so effective? A short connection to
(clamping to) earth ground determines effectiveness. Earthing being
the protection. Protector being nothing more than a temporary
connection (clamping) to protection. Protector being only as effective
as the protection it connects to: earthing.

To provide both conductivity and equipotential, the clamping of a
typically destructive transient is best distant from protected
electronics AND as short as possible to earth. Such protection
effective for all type of transients - and costs many times less money.