Is it an either / or situation? You have multiple pools of listeners, with an unknown amount of overlap. You can post your messages to each pool and reach people that would not otherwise receive your message.

I don't know why people feel like Nostr must compete with Threads, the Fediverse, Bluesky / AT Protocol, Twitter, Instagram, Gab, etc. It stands on its own and needs no comparison to establish its value. So do most of the others.