IIRC it’s among the first things they onboard you about. It’s also in the share menu, you should have seen it if you ever tried to download or share a video, or create a duet, or something. Long press is just an easy way to bring it up. Given the percentage of people commenting on TikTok threads who’ve never used it, “first time I heard about it” doesn’t mean much.
First time I heard about it. If it's hidden behind an undiscoverable gesture/tap, it's not accessible.