[dwohnitmok]

It's not necessarily a northern Chinese centric view of China as it is a Mandarin (as in the language family) view of China. The vast majority of Chinese dialects in a large band from Heilongjiang to Sichuan (and a bit out to Qinghai and Xinjiang) are more or less mutually intelligible. That mutual intelligibility drops off very quickly outside of that band. In particular a lot of Southeast dialects (Yue, Wu, Min, etc.) fall outside of that zone. But it covers the majority of Chinese speakers. (However, I disagree with the original claim that a Sichuanese speaker could understand Shanghainese).

See e.g. this video: https://www.youtube.com/watch?v=Ps7_NnkL-oM where for almost the entire video a couple is explaining words in their respective dialects (Sichuanese and Hunanese) to one another in their own dialect (i.e. not using Standard Mandarin at all in their explanations). The first half of the entire exchange is fluent and understandable by both people and also a Standard Mandarin audience. Only in the second half when they intentionally start quizzing each other on words they know will be tough for the other person and without additional context do they run into trouble (and occasionally resort to Mandarin).

Also, comparing it to Romance languages masks some complexities of the relationship. https://news.ycombinator.com/item?id=16844074