TBH, you should treat them as if they don't ("size of part library shouldn't be part of the evaluation, let alone top of the list of "standard questions"). And generally external libraries are suboptimal as well, for various reasons. What I want is tools for quickly importing and generating footprints, like Altium's generator (and support for mechanical dimension constraints like mechanical CAD has had forever would really help. It boggles my mind that no PCB tool has them, it would be such a killer feature)