Currently Kagi can't compete with extensions like uBlacklist, when it comes to domain blocking. Trying to handle large amounts of domains is currently very difficult due to the lack of support for bulk editing and removal of domains. The ability to import public rulesets, similar to Subscriptions in uBlacklist, would make the sharing and editing of domain blacklists/whitelists much easier.
For full compatability with existing blacklists, Kagi would need support for Match Patterns and Regular Expressions. These two features by itself, without the support for importing lists, would already make Personalized Results in Kagi a lot more powerful.
Currently it is not uncommon to have large amounts of repeated domains in the Personalized Results, such as:
pinterest.com
pinterest.at
pinterest.be
pinterest.ca
pinterest.co
pinterest.ch
pinterest.cl
pinterest.de
...
Instead of manually adding these domains, users could import public lists like this. Lists like this could also be simplified to a single entry using RegEx:
/^https:\/\/\.pinterest\./
These options would make it much easier to handle large amounts of URLs.