Earlier quoted context omitted.
> There can be a decent turnaround lag (sometimes on the order of a few days) Actually, the link says > Files submitted for signing will go through an automated review process. If they pass this review, they are automatically signed and sent back to the developer. This process should normally take seconds You may be thinking of a different type of review process, the signing one sounds almost instantaneous.
That's for non-public add-ons. If you submit a public add-on, even a minor update, it has to go through the AMO bureaucracy. I currently have an update that was uploaded on July 10, 2015, and is at queue position of 64 of 137. There are no code changes; it's just being updated because Mozilla changed their build system. This seems to be part of Mozilla's effort to be more like the Apple and Google stores. Mozila AMO…
Addons are running in the chrome context and are thus pretty powerful. It's trival to compromise the whole computer if they aren't reviewed.