Doug,

Think about the mechanics of both your statement and mine

By using the topping lift for Hoisting the total strength of the Rig is
used (Shrouds, fore and back stays; In my case double lower shrouds to
keep Mast in line.
With the Rigid Vang in Hoisting, you are putting Max Effort on the end
of the boom, supported at a point about 1/4 of the way back from the
Gooseneck.
That is an awful long unsupported Alum. Pole. (Hollow Aluminium Pole).

In operation, the force of the sail is at least two points on the boom,
with the main sheet countering the force on the boom. Often assisted by
the Vang. Often over assisted by a Hydra. Rigid Vang.

I'm sure, as an Engineer, you can admit to the difference

If you were careening the hull, you wouldn't weight the end of the boom
without the back-up of the topping lift and/or a halyard to call on the
full strength of the total rig. The topping lift is a solid connection.
The halyard is a varying force

Just some things to remind you of.

I'm not knocking the Rigid Vang. I wish I could fit one on my boat but
the Pilothouse makes that impossible. I'm thinking I might be able to
use a KICKER. I'm pointing out that PITA top lift still is a worthwhile
addition.

Ole Thom