I worked on such a thing in 1996 or so. The company was Mango, the software was Medley. It worked pretty much like you describe, and it was a *real filesystem* unlike blb. About the only think blb has that it didn't was erasure coding, because that was hardly a thing back then (I personally didn't hear about it for another four years or so). Wouldn't have been hard to graft on, though.
Every year or two there's a new blob store based on the same old ideas, claiming unprecedented levels of scalability, reliability, and convenience. These claims *always* turn out to be exaggerated. Some of the offerings are fine, just not as fantastic as they claim to be, because it turns out this stuff is actually hard. (This is what I do for a living, BTW.) If it hasn't actually been run on a multi-thousand-node cluster, it *won't* run at that scale and probably won't run for very long even at hundreds before it loses data. FWIW, I wrote a bit more yesterday about the *absolutely predictable* issues/omissions I found in five minutes of looking at the blb source.
There's nothing actually wrong with blb. It looks like a decent starting point if you want to build a truly high-scale object store for fun or for internal use. It's just not as All That as they claim.