Relays are no different than any other hosting service in terms of incentives, they're a CDN for notes.

Some hosting services cater to illegal content, like seedbox services for torrents.

Others, like business tier S3 with a terms of service, do not.

The only difference vs. traditional hosts is that Nostr uses keys/signatures so that data is verifiable and therefore can be easily distributed across redundant hosts (exactly what torrents do by using redundant trackers with hashes to ID files).

Unlike torrents though, there's a reputational lever available in Nostr because of author keys. This will allow it to become more email-like, where servers generally drop everything that doesn't pass some checks.

Email and traditional file hosting is enured to legacy DNS/IP4 limitations, and therefore not as simple to have provider redundancy, which makes service offerings less commoditized than is possible with Nostr relays.

So, while Nostr is an improvement over legacy hosting services in terms of censorship-resistance, there's no magic that makes it a different animal in terms of incentives or how it evolves service hygiene.