What problem does this feature solve?

The default behavior inheritAttrs: true is almost never the desired case for encapsulating components, I have to set inheritAttrs: false for pretty much all components that I write in real projects. I understand making inheritAttrs: false the default would be a huge breaking change: https://github.com/vuejs/rfcs/pull/26, but at least provide an option to set inheritAttrs: false globally for all components.

What does the proposed API look like?

app.config.inheritAttrs = false

I believe that most userland applications require inherited attributes. Like Only 8 files have inheritAttrs set in Elk.

Perhaps we could include an option to change its default behavior.

This affects all Vue components inside an app including third-party ones. I'd say setting inheritAttrs: false at global level has a fairly big chance to break some of them but the problem it brings can be very hard to identify and locate.