Alternative to excludedLocalNames?

[morethanreal]

In #3, @cdata says about excludedLocalNames:

This is kind of a clunky way to expose the exclusion list to an element that uses this behavior and wants to exclude other things. The element author needs to know that the old list contained template if they are over-writing it in their element. 🚴

Explore a better option for this.

[valdrinkoshi]

Instead of excludedLocalNames, could we exclude items that have an attribute like disabled or exclude?
template, style, script elements should always be excluded
@notwaldorf @cdata @bicknellr WDYT?