But it's not measuring link speed directly. It's measuring transfer rate through TCP which is byte oriented. It's not possible to receive partial bytes via TCP (or UDP for that matter).
I don't measure file size in bits. I don't want to multiply/divide by 8 when roughly estimating how long a download will take. I end up doing 10 instead for maximum ease and pessimism.
Link speed has always been measured in bits/s or as sibling comment suggests baud which is, still, just bits per second.
Obviously a huge part of this is marketing for modems, ISPs, network cards, etc. but it’s consistent. The conversion to GB/s is fairly simple and doable with the super key, or super space on Mac in every modern OS…
I agree with you that the difference is irritating, but wouldn’t have done any different if I were Cloudflare.