In some scenarios, users want standalone packages that are unaffected by their parent package (#6646). Having package.workspace = false for that would be less invasive than adding a [workspace] table:

• cargo new underneath it won't get that package added as a member
• Doesn't require the user to engage with as many concepts

Maybe this should be made the default for cargo new for packages that aren't added to a workspace?

Cargo script will benefit from this when we introduce workspace support to it. Currently, they can't be part of a workspace, even their own. Its like we had package.workspace = false. When we want workspace support, we'll also want a way to turn on normal discovery (like a package.workspace = true).