List of TX/RX bandwidths on RB951

Using 951G-2HnD w/6.26.

With the /interface ethernet bandwidth setting, why is the list of speeds as it is? A bunch of choices 128k-10M and nothing else. Attempting to set anything is not accepted. I guess this is not a limit of the chipset as the datasheet says:

The AR8327 can limit all frames and support rate limits from 32 Kbps to 1 Gbps at 32 Kbps granularity.

I guess I could create queues and whatever to do arbitrary rate-limiting, but why is it so limited per-interface?