[jameshart]

Nobody knew BASH enumerated every environment variable and - depending on its content - maybe evaluated part of it for immediate execution.

It wasn't documented and it wasn't expected. It's not part of the expectations people have for a POSIX shell.

In your metaphor, it's more like the ice cube manufacturer has been making brick-shaped ice cubes and selling them through building suppliers, and they've been widely used as a building material for many years and the ice cube maker has never said anything about the slight risk of it melting at room temperature.

What you're arguing is that bash is not and was never a solid POSIX shell.