With welding you are introducing another metal into the signal chain. This is likely why the big budget cable you reference is using a set screw...a more purist approach.
BJC interestingly enough, now has a line of cables that sell for a few thousand dollars a pair....using Cardas solder. If you can’t beat them, join them I guess. ;-) https://www.iconoclastcable.com/
WBC uses many brands of cables and connectors so your experience would only be relevant to the wire and connector combo that you tried...which I don’t believe you have disclosed.