On a disc brake bike, calipers are ~100g, rotors ~120g, and then you’ve got ~150g of tubing/fluid. They’re certainly heavier, but the components don’t even add up to 1000g, nevermind when you offset the rim brake component weights.
No need to get emotional over this stuff, I love my hydraulic discs but they are heavier at comparable price points. It's also not particularly important to have a bike weigh a bit more, I was just letting the OC know that he was wrong on that aspect.
So to add it all up you’re looking at 770g in components/additions, offset by 75g skewers, 310g calipers, and an added 25g or so per rim for the brake track. So discs are naively something like +335g. I obviously agree it’s a heavier system, but I don’t think ballparking the penalty as triple what it actually is is reasonable.