The Nikon film cameras metered TTL off of the film plane too. Not being able to do that now (aliasing filter shut it down) forces digital to use and meter a weak preflash, which I'm not sure is an advantage (seeing the actual flash in real time seemed a plus). Now the digital system has to tell the remote flash "whatever you just did, now give me 6.2 stops more than that this time." It cannot ask for 1/4 power, because it has no clue about total capability. Speaking of the Commander, even if knew what it was (it doesn't), it does not know where it is either.
However, every cloud has its lining. The new system does allow metering flashes individually, which the film plane system simply could not do (not if confined to real time). The film plane could see how they all add together, and could see when the total was correct, but the new system lets us control each individual flash, and to know and control the ratio. The old system could not do that. And lighting is about ratio.
The commander does try to set each light (each group actually) to be equal at the subject, but then the commander menu also has the ratio settings in it, to specify a fill group is to be a stop or two down from main. Metering individually cannot see how the setup actually overlaps and adds in highlights, but it's about the same situation as using hand held light meters (except they are incident instead of reflected). And handheld can meter the total too.
So now you don't have to know the 1.5 stops difference, and don't have to set them at equal distances. You really don't care about that, you can simply tell the Commander what you want, how you want them set, how you want them to meter at the subject.