Even in todays high end market it is rare that a cable manufacturer makes their own connectors made particularly for their cables.
Instead they choose a standard component made by a third party.
This leads to constrictions on the design of the cables and in many cases fit and finish that are several steps from being “high end” because they are covered in layers of heat shrink that compensate for poor strain relief and/or mismatch between the cable and the connector
As you have without doubt noticed in your trip through the audio world many cable manufactures have a very intense focus on the purity of the metal used for their conductors. leading to claims of 99.9999999% purity by some manufactures.
However, the connectors that are mounted on these high purity cables are surprisingly often made of metal that is a copper alloy such as brass, bronze, and in the best cases Tellurium copper.