How many can you block and filter manually ? 10 ? 100 ? 10k ? Who will test sites for the blocklist ? The domain block feature is great but unless it's collaborative listing it's not gonna be super effective.
Also they do share the most blocked/raised/lowered etc sites: https://kagi.com/stats?stat=leaderboard
We've had this problem of "good defaults" before with ad trackers blocking domains. I'm sure it'll be Sooner than later when some community lists become popular and begin being followed en mass