[ken]

There are 4 reasons proposed for the failure of OODBs, in that paper, but scalability is not among them.

Interestingly, the issues are largely C++-specific (and I know lots of people using an ORM today but none via C++), and largely driven by historical accident and market forces ("It is interesting to conjecture about the marketplace chances of O2 if they had started initially in the USA with sophisticated US venture capital backing").

I still don't think these sound like good reasons to dismiss the architecture.