Pubkeys that have only a few followers would be more vulnerable to denial-of-service than those with many followers. Each follower could help extend their distributed-ness and robustness.

This is also how Nostr relays are becoming more denial-of-service resistant. If Alice can write to her own relays and in addition to the relays of those that follow her (directly or indirectly), her profile and notes are more robust. For notes/events that are reposted, this could increase even farther.

For kind-0 (profile meta) and kind-10002 (relay listing meta) events, the replication could automatically extend to not only followers, but also to followers of followers and etc.