I'm not against the idea of 1x specific drivetrains. If you have SRAM Rival or Force 1 and you can have it set up for same gear range as a compact double but simplify by not having front shifting it makes some sense. But even then cassettes to mimic full range of a compact are in the 400-500g range so that negates weight savings of getting rid of front derailleur and front shifters parts.

The places that I see it making more sense are the target audiences of mountain bike, cross and crit bikes. If you are racing crits which are mostly flat then you can get some weight savings since you can go with a smaller range cassette. If you are racing cross or riding mtb then not having a front deraileur that can get banged on a rock or tree stump and brake or mess up your shifting seems to make sense. But just doing it for the sake of doing it or trying to make a 1x drivetrain out of parts that aren't build for that makes no sense