I haven't seen a single social media or messaging platform where search didn't suck. Reddit search was bad, after redesign it's just hot garbage. Messenger search is unreliable and near-useless. Facebook search only worked well for the brief moment when they introduced "graph search", but that got quickly killed due to popular outrage. HN's bolted-on Algolia search is the least bad I've seen. And let's not even talk about Twitter, Instagram or Slack.
I'd go as far as saying that search features are being underdeveloped on purpose - perhaps they allow usage patterns that service owners don't like.
But then, Mastodon's search is even worse than Twitter, and that project has no incentive to disenfranchise their users. So I'm honestly confused about all this.