"various restrictions on them, such as displaying authorship, or reciprocation, or patent grants."
Those are for the greater good. Saying you are not allowed to use the source code for commercial reasons is discrimination and that isn't allowed according to OSI. I'm cool if you don't wanna use OSI as a rule of thumb; but then my alternatives are FSF's free software definition, or DFSG.
We're discussing source code; so whether something is OSS or not refers to open source software; OSS. The last S is usually omitted, but it still refers to open source software.
> I think almost everyone would agree that CC-BY and GFDL are open source licenses, despite them not being on that list.
These have nothing to do with open source. They might be in the spirit of open source at best (in the situation of GDFL and text), but that's it. Documentation cannot be open source, and GDFL can actually be harmful in that context.