Ha, yes, I've done that at https://gigablast.com/ . The biggest problems now are the following: 1) Too hard to spider the web. Gatekeeper companies like Cloudflare (owned in part by Google) and Cloudfront make it really difficult for upstart search engines to download web pages. 2) Hardware costs are too high. It's much more expensive now to build a large index (50B+ pages) to be competitive. I believe my algorithms…
So my suggestion would be to lower the weight of the ranking of the domain, and promote sites which have a more recent update date.
Send me an email (contact in profile) if you want to follow up on this feedback!