@Nevis1 -
I also agree with @Matt.
I would think that Backups as part of core strays much too far into plugin territory.
To my understanding, core development is centered around creating better ways to create content.

The WordPress team already does a ton of work to make sure that core is as server-independent/compatible as possible. Backups in core would require a whole separate team to develop considering the wide range of scenarios that backup plugins have to cover.

tl;dr: Core is all about being a lean, mean, content-creating machine. Plugins (like backup plugins) extend upon that.