I'm having trouble imagining that Google would be more limited by the ratio of hardware power vs data size today than it was in the early days. If keeping the whole index in DRAM is now a requirement, then yes, I'd expect a hugely reduced overall dataset - but wouldn't that affect way more sites/pages than the comparatively few dropped historical records?

I still suspect that this whole thing is more about bias (and personalization, be it correct or incorrect) in the results.