Enable container specific saved passwords

I’ve been using firefox containers for a while and they are really useful. However, one use case that they currently don’t work well with is saving passwords for websites in only the current container.

https://wiki.mozilla.org/Security/Contextual_Identity_Project/Containers specifies that this is intentional. Could someone clarify why this is, or ideally provide a mechanism to support this? Would exposing this functionality to 3p developers who can build addons be an option?