I suspect having access to a 1:1 ratio is pretty useless for enthusiasts. If the chips could reliably run at 1:1 with high RAM speeds, they would be already. As you say, it might be useful for someone with 2133 MHz DDR4 but I doubt you're gonna be able to run 1:1 with 3466 MHz DDR4, for example. Making it actually tweakable with certain multipliers would be much more interesting.On early developer platform X370 boards there was an option in BIOS to switch the IF ratio between half memory rate (what all Ryzen 1's are currently locked to) and 1:1. This was then subsequently removed from BIOS before retail boards were launched. This sounds like it will be a more refined version of that option, which would be a great help to those on low speed memory, but want to get the improved performance that comes with increasing the IF speed between CCX's.
P.S. I notice Silicon Lottery and planning to sell both R5 2600X and R7 2600X binned chips so we'll find out eventually what the overclock range is for them!