Cat 6 speaker wire. Gem in the rough.

Some of the best cables I have ever heard.

Cat6 with FEP insulation has been a long decade favorite of mine.
With cat5 another major breakthrough is realized in sound quality even with a non superior jacket material.

Recording a live event can be very demanding on a speaker cable and if the Board man is unfamiliar with the speaker cable and speakers used, the sound can be altered from one recording to another with the same material. Especially with non powered speakers "which I build and Prefer" to powered speakers that use Class D amplifier designs. Without throwing everything into a tizzy, most studio monitors in recording studio's are now powered and most use class D. The reason, cheaper more power less weight, and in my opinion weaker, dirtier and uninvolving , and the loss of warmth even in the new digital era.
I consider this a lost art.

Lets go back to when say Barbra Streisand recorded in the studio with an amplifier speaker wire set up. Say SSL board studer a820 Crown amps JBL L300's or Altec's and high end lamp cord. The sound was simply mind blowing, alive and full of emotion.
This is the feeling I get today with properly designed speaker cables and Cat5 and Cat6 definitely take the cake for price versus performance without getting into the exotics that cost more than the equipment!
..high end lamp cord
So the lamp cord of the '70s is the same as your Cat5 or Cat6 cable?

I don't think most studios care much about weight, and the higher end studios probably don't care about cost too much. Take a look at the JBL M2 . Producers want flat flat sound to avoid any coloration in the mix. JBL is using Class D amps and a DSP to achieve this. The speakers are still passive but need an active crossover to control them. The L300's, while expensive at the time, could only dream to be this accurate.
Crimson Audio speaker cables are made by a company that makes Cat6 cable. They are very close in design, from what I've been told.
Class d amplification is still pathetic in sound quality, and is very popular in the poor mans studio but Dynaudio is almost getting it right at Air Studio's in one of their control rooms.
Scvan, the graph you showed could be had for a vifa tweeter with Lowes carol cable?
Experimented with Cat 5, 20 years ago (worked for a telecom company). Used Plenum Teflon grade. Very bright and edgy sound. Preferred stranded copper PVC speaker cable. Much better choices out there today.