Why high-end cable manufacturers don't post measurements?

Mr.  ieales

You are so wrong!
https://en.wikipedia.org/wiki/Damping_factor
DF is per definition: "Only the resistive part of the loudspeaker impedance is used. The amplifier output impedance is also assumed to be totally resistive".
You want to go into L & C?
Go.
I'll stick to the rules. 
As so, R/R = pure number (DF) it reflects a ratio.

More than that, if you go deep, you will find out that by looking into the Amp's output, through the Speaker cables, the loudspeaker is irrelevant.  
The cables do not care what loudspeaker impedance they drives (Z).

You really think that all cable makers do Bode plots B4 releasing a new cable? 
All the sudden, you take a subject ( Speaker cables ) and try to test it, or calculate it, in ways no maker ever did? Good luck with that. Bring it in if you did.

By understanding the way it works, you can skip it. Trust me on that.
I've told you already what matters: DF and length, to calculate the #AWG.
It works 100% of the time.

Mr.  auxinput

It is no religion. It is science. Once you will be able to tell the difference between the two, and be willing to try it (religiose won't, scientist would!) you will no longer stand in the shade and go against everything you don't know. 
You try to say "NO" on something you never tried, nor understand, just because it may collapse your entire world.
A world based on superstition and industry lies for decades.

b4icu:
bewildered 4 i can't understand?

A/C signals react with LCR. If they didn't, crossovers would not work.
L & C are squared terms, R is linear.
Your cables have MASSIVE L & C and are thus tone controls.

Damping Factor is DC.

Mr. ieales

I know music is AC. Those who claimed that their cables are directional don't! What a shame...
On the analysis, when looking from the Speaker side, back into the Amp's output, through the cables - the Speakers are insignificunt. 
They are not part of the deal.

Now let's take a twist on the subject:

You never tried my idea. NEVER!
You have no idea what it sounds like.
What improvement it does.

But you still nugging about every parameter you can grip, just to go against it.
Why?
Those who tried, still have a pleasant smile on their face and enjoy a way better sound.
So what is your mission or drive?