The proposed replacements don't always work. Using `$()` doesn't handle if the command exceeds the max size for a command with it's arguments and environment.

The proposed replacements don't always work. Using `$()` doesn't handle if the command exceeds the max size for a command with it's arguments and environment. Piping to bash has its own problems, like needing to escape things properly and hope your input doesn't have any special characters.