When designing an app, everyone looks at how other apps do it today. However, incumbent apps operate in a different context: they already have habit formation and many of their aggressive growth hacks have been eliminated due to public scrutiny.
Instead, using Internet Archive and old blog posts, find older screenshots & marketing materials when the incumbent app hit their inflection point (e.g., Snapchat in 2012) and construct a narrative on why they did what they did. You’ll be surprised by how explicit they were with their value proposition.