your conclusion makes no sense.

1st, sata doesnt "run" off the 3.3v rail, and Molex doesnt "run" off the 12v rail.

MOLEX contrains both 12v and 5v power sources
SATA contains 12v, 5v, and 3.3v power sources (but the 3.3v is rarely used by anything, i doubt the risers even use it)

most risers with a 6-pin connector come with either molex or sata to 6-pin adapters. guess what, they ONLY use the 12v lines and have Vregs on the riser to drop it to lower voltages.

people heres are die hard anti-sata for some reason. yeah you can have some problems with low quality components, but daisy chaining and using SATA adapters isn't insta-death like some would have you believe.

my first rig has been running for MONTHS in the perfect storm of "bad" configs. 8 GPUs, V006c risers (6-pin power) using SATA->6-pin adapters. running 2 SATA cables from the PSU, with 4 risers on each line (from a very high end 1200w plat PSU with metal barrel connectors). it's fine *mic drop*

the biggest problem is getting enough 6-pin connectors in most cases.