Well on pubky you've got both options, atomic (signed notes) and non-atomic (signed space). So you pick the trade-off you want. If you choose the atomic option on pubky then it'd be no different to nostr in terms of everything being a signed event, and the trust involved. On nostr you only have the atomic option. Nostr one option, Pubky two options.

Verification of events still happens, but through the location, not individual events. It doesn’t degrade trust at all. And it increases safety and security. Only benefits.

you mean every time you receive a note you have to go on a server and ask if it's valid?