Centralized social media platforms engage in content moderation that could in some cases undermine the freedom of speech. Twitter is a prime example of this, with many documented cases. I don’t see that problem with Nostr.
I don’t disagree that there is a bigger network effect with other platforms—they’ve been around for far longer. But I also don’t know that Nostr needs to replace them. Is that really the problem that Nostr solves?