A lot of big tech apps launch and try to be something else. Tiktok grew with its own design goal and its own site culture. You cannot rip a site and rip its culture and expect people to want to join the knock off.
Take a look at X vs bluesky. The only reason this works is because the site culture changed enough for platforms to be different enough to warrent leaving one for the other.
Snapchat is right there, as is reels and YT shorts. Microsoft conceded and just paid twitch because their own thing wasn't working. A brand is a moat that's hard to definite. It wouldn't be too difficult to stand up an alternative to Twitter or Reddit, but getting the people to move over there is the problem. What happened to Vimeo?
At some point, Vimeo was known for having higher quality video formats. But I'm pretty sure you get the same if not better on YouTube today.