Comparing with norwegian is not straight forward, as Norway has both 'bokmål' and 'nynorsk'.
If danes startet speaking like text was written, the language would be much easier to learn.
Or we could invent a common nordic language.
@Chris I don't think the difference between bokmål and nynorsk is too relevant, given that the article was focused on spoken language.
I think the reason they used norwegian as a comparison to danish is that they're very similar in terms of syntax, grammar, and vocabulary, making it easier to attribute differences in listening comprehension to differences in pronunciation.
The thing I found most interesting is that it's not just about learning, but also applies to adults who grew up speaking danish.