that’s not what I’m looking for when I’m looking at a backtrace. I don’t mind plain unwraps or assertions without messages.

You're assuming the PoV of a developer in an at least partially controlled environment.

Don't underestimate the power of (preferably specific/unique) text. Text a user (who is more likely to be experiencing a partially broken environment) can put in a search engine after copying it or memorizing it. The backtrace itself at this point is maybe gone because the user didn't care, or couldn't copy it anyway.