Docker or containers in general provide isolation too, not just declarative image generation, it's all neatly packaged into one tool that isn't that heavy on the system either, it's not a cop out at all.

If I could choose, not for laziness, but for reproducibility and compatibility, I would only package software in 3 formats:

• Nix package
• Container image
• Flatpak

The rest of the native packaging formats are all good in their own way, but not as good. Some may have specific use cased that make them best like Appimage, soooo result...
Yeah, no universal packaging format yet