I can't argue that Signal adoption rate hasn't been fantastic, but the paternalistic "opinionated" crypto has always rubbed me the wrong way. I remember the initial announcement claiming that binding themselves to Google Play was "more secure" because it would lead to more adoption. This is of course patently absurd when Google is one of your primary threat actors.
My "mobile phone" is not the center of my digital existence, and never will be. When I am home I leave it by the door, and use different devices - desktop, laptop, and a different pocket device for photos, afk, messaging, yardwork music, etc. So similarly, this argument that Signal is super sekoor by relying on treacherous hardware enclaves etc just falls super flat. If I'm not able to choose between competing open clients for each of my use cases, then I will always consider your system as a proprietary nuisance that I just need to mitigate my exposure to and cope with otherwise.