> bulldozer
This might be true. The complaint about Geocities sites hogging the G serps came largely from SEO's and maybe corporate types. In many ways, the free sites were a collective Wikipedia before Wikipedia was ever thought of. They were established long before Google, the best were listed in Dmoz which Google leaned on heavily and the Geocities type sites were well linked together as a legacy of surfing the web before competent search engines. This made the best of the free sites rock solid for the original PageRank.
They were also in the way. Geocities webmasters were never going to buy Adwords. Paramount wanted their late to the web Star Trek site to rank higher than Fred's Trek Fansite and SEO's wanted to rank for words like Orlando and Miami to sell something and there was always a free website getting in the way.
I remember some sort of announcement at WmW, perhaps by a Google Minion, that the free hosted sites would no longer be cluttering up the serps. And it happened. It wasn't personal, it's just that Geocities, Tripod and such were in the way. The free sites were there for fun and free exchange of knowledge but the web was turning commercial and needed to be paved over into the vast asphalt parking lot we have today.
> diversity
Spot on. The lack of search engine diversity is a huge factor.