Another problem with everyone doing a search engine is that they can have a widely-disparate featureset, and I’m very unlikely to spend enough time on any one site to familiarize myself with a given featureset. Maybe one or two sites, like github.com. But if I’m just looking for a download of software for a given product? Nah.
Maybe if everyone used local Search Engine X – like Harvest or something. Or if everyone agreed on a search syntax to support.
Google also used to, in their early days, sell a search appliance that companies could use locally to provide searching. I’d guess that that probably contains enough trade secrets and stuff now that they don’t want to hand it out any more.