It is essential that 3rd party wikis have a contact form.

[Citation Needed]

It's one of the many reasons we have a extension system, as every MediaWiki can be different and need/want different features instead of just bundling every possible extension which makes the core download bundle even larger.

Subask of T392080

As requested previously, Please actually set the subtask status properly, instead of freehand writing it, so the dependency trees are generated. If you require help with this don't hesitate to ask.

I also assume you mean Extension:ContactPage which exists and not Extension:ContactForm?

Extension's default configuration provides optimal experience

I would disagree with this. For a wiki to define a MediaWiki-extensions-ContactPage they have to set site configuration in a way which is complicated. Only after T386652 would I feel that this point is met.