A French octet is a byte. The b here is a bit.

I really like the idea of having distinct abbreviations for bytes/octets and bits!

Seriously! If I see something like mbps written I have to wonder whether it's saying megabits or megabytes per second. Bits is more likely only because it gives a higher sounding number, but outside of marketing either bits or bytes is equally likely.

We do: b for bits, B for bytes. People are just sloppy when using them.