Well, as a northern guy, I do find myself able to understand Mandarin even from Yunnan easily without prior learning. The harder ones for me, like the Hefei dialect, are because the pronunciation is very different, not the tone. Nanjing dialect, on the otherhand, is also from the same Jianghuai Mandarin group as Hefei, which is perfect intelligentable for me.

Even for non-Mandarin/Guanhua, such as the Shanxi dialect, I can understand them because the pronunciation is much closer to mine, just the tones are completely novel.

> If you have all the tones messed up, you can hardly communicate in Mandarin.

> To a considerable extent, Mandarin exists because of tones. You cannot communicate in it with messed up tones.

These statements are false. If they were true, it would be impossible to understand written tone-free pinyin; in reality, it's not just possible but easy.

Yes but Regular Mandarin has different tones, Beijing Mandarin is not Hong Kong-style Mandarin is not Taiwanese Mandarin and so when a foreigner chooses "Reference Mandarin", they are choosing what, exactly?

Point being, this idea of a Universal Reference is exactly the kind of linguistic erasure that is wrongheaded to begin with. Nor does this completely prevent comprehension, these debates underestimate how much human communication is contextual, you read what I wrote above and most of it was your mind already filling in (gasp, like an LLM) the next words enabling you to read relatively quickly.