Facebook is ripping off a larger variety of apps than WeChat, it seems more like they're trying to push into Snapchat's market share.

I'm not familiar with payments being a feature on iMessage or Messenger, though. Unless you mean just the money transfers to friends, which existed on Facebook's desktop Messenger first IIRC, so it doesn't appear to be ripping off WeChat (which in my experience doesn't really support money transfers in quite the same way, unless we're talking about hongbao).

Also, weren't stickers a thing on Kakao Talk and LINE before WeChat?