> In fact many would argue Chinese languages were never unified (mandarin/cantonese/etc) but the scripts were.

This is, in fact, the default stance held by most non-CCP linguists. If you read what experts in the Chinese language family say, it's basically "Chinese languages are mutually unintelligible and more distinct than the Romance languages, but because the government of China says they're just dialects and we (as linguists) recognize that the line between dialect and language is basically arbitrary, we'll call them dialects so we can just study the languages and avoid getting sucked into nasty political discussions."

As the saying goes, a language is a dialect with an army and a navy—and this works both to define distinct languages that are otherwise mutually intelligible and to merge dialects that aren't.