You keep coming back to how heavy electronic is, but I’ve never seen numbers that back it up. The crank, cassette, and chain are shared between mechanical and electronic and that’s where the vast majority of the weight savings are as you go from the lower groups to the higher end stuff. If you just look at the electronic bits (RD and shifter), I believe the weight difference is under 50g when comparing mechanical and electronic from what I recall.
If you want to compare old mechanical eagle to new mechanical transmission, there is certainly a big weight difference because SRAM doesn’t sell high end mechanical transmission groups (because there is basically no market for high end mechanical).