Here is what was specifically written:
Rating Type “B”: This rating type will no longer be published but process will remain unchanged. Championship players will not be allowed to appeal their ratings down for one year after playing in Championship matches but will be allowed to appeal their ratings up if they otherwise qualify.So benchmark calculations are still done, they've just elected to not publish who is/isn't a B. And they've also made it so benchmarks can be eligible to appeal up.
I'm guessing this was done because people were confused by who was/wasn't a "B" or what it meant. So they just removed it so it isn't published.