Every connector is a point of failure so I prefer to minimise them as much as possible.
That's false if reducing the number of connectors increases the load on each one, which is exactly
what you are proposing.
What you're saying is nonsense. I never said it increased the load but every connection is a point where 2 metal surfaces meet. This is inevitably a weak point compared to a continuous cable. An imperfect mating or a bit of corrosion can cause localised resistance leading to rapid overheating and a melted connector. Over the past 3 years I have seen it happen 3 times, all within the first 2 years I have learnt the hard way to reduced connections as much as possible and have seen a corresponding improvement in reliability.
Connectors, especially cheap connectors are by far the biggest danger. So the fewer you can arrange to have the safer.
None of the more recent cards work with one less 8-pin plugged in, but I think almost all of of my RX580 cards that had 2x 8-pin or 8-pin + 6-pin worked fine with only one 8-pin plugged in. I can't remember all of them, it wasn't many. One was a Sapphire.
Finally some useful information! I suspected some cards might be hardwired to insist on both connectors being used. The only alternative would be a daisy-chain. Not ideal but I will certainly consider it as I would like to try one of the new RTX3060ti's and it's almost impossible to get one ATM.