FWIW, lots of power connectors are indeed only rated for a low number of mating cycles (only 30), not just 12VHPWR. This includes the old PCIe 8 pin (same 30 limit). Realistically you will probably not reach the rated limit.

The actual problem, I think, is that the connector could operate without being fully plugged in, especially without current balancing on the side of the card. This is an actual fire hazard, as you now get at least some connections with very high resistance, forcing extreme current on the remaining wires with low resistance connections. This is combined with the fact that the safety margin on 12VHPWR is a lot lower than that of the PCIe 8 pin (which I believe can safely carry a lot more than its 150W rating).