Being Nostr-only is also a terrible strategy to promote Nostr.
You are then only posting to people who already know Nostr (because they are on Nostr). It's a bad idea, it's limiting.
Also, Nostr isn't perfect. It's good to explore different decentralized and censorship-resistant options which may already exist or exist in the future.

There isn't one *specific* platform, or protocol, or really one specific anything that is inherently better. What is inherently better is always something which, if it were forgotten, could be built again. So it's decentralization and censorship resistance, not Nostr specifically.