For the average user (GPU + NVMe + SSD) 16 + 4 is perfectly fine and there's no noticeable performance lost out nor have I ever experienced any issues with several builds. There's little to be gained for these users. I suppose the option to free up lanes may be handy, but certainly not a game changer.
However, if you have multiple GPUs, multiple NVMe drive and external USB 3.1/Thunderbolt storage etc, then yes, there's going to be a benefit. But you'd hardly have an average sort of build and be looking at a HEDT workstation build anyway.