The point is that if you say “Debian 9” it is immediately clear what version it is and what’s the context today as long as the person knows the stable is 12. If you say “Debian Stretch” it’s just noise, random words that mean nothing if the other person knows that stable is Bookworm.
You can just use “stable”, “testing”, and “unstable” if you prefer. And I don’t just mean in conversation I mean update /etc/apt and be done.
But there’s been at least 10 versions of stable
The point is that if you say “Debian 9” it is immediately clear what version it is and what’s the context today as long as the person knows the stable is 12. If you say “Debian Stretch” it’s just noise, random words that mean nothing if the other person knows that stable is Bookworm.
I run Debian and I don’t know what number or Toy Story character I use. I know I’m on testing, so I say that.