Does a foreigner need to understand different accents of Mandarin?

[wraith hinge]

80% of the population of China speak Standard Chinese. Does this indicate that a foreigner does not need to understand different accents of Mandarin, because 80% of the population of China speak with similar accents, which is overwhelming majority of the population?

For example, whether the Mandarin accent pronounces the Pinyin initials <b> and <d> and <g> as [b] and [d] and [g] instead of [p] and [t] and [k] respectively does not matter and is still a standard Chinese accent, because there is not any confusion with other sounds of Mandarin, but whether the Mandarin accent pronounces the Pinyin initials <zh> and <ch> and <sh> as /t͡s/ and /t͡sʰ/ and /s/ instead of /ʈ͡ʂ/ and /ʈ͡ʂʰ/ and /ʂ/ respectively matters, because there can be confusion with the pinyin initials <z> and <c> and <s> respectively.

[marble dune]

If someone's Chinese is good enough, they can infer the meaning from the context, which is how Chinese people do it.

In my opinion, if someone can't even infer the meaning from the context, their Mandarin must be terrible.

[peak breach]

tbh most native speakers of Mandarin have trouble with (thicker) accents unless they're pretty cosmopolitan

so it really depends on what you expect to use Mandarin for. If you expect to deal with a diverse bunch of Mandarin speakers, then it'd help to get used to different accents

[still roost]

Or is it because the vast majority of pronunciations in other spoken dialects are the same as those in Mandarin, and the differences in words—whose nuances can be inferred from context—do not hinder communication (with Cantonese being an exception in this regard)

[upper stream]

depends on where you go really if you go to shanghai maybe try listening to that accent as much as you can because if you are not exposed to an accent especially more southern/rural accents can be really difficult if you're only exposed to standard/broadcast mandarin