If you research how their name came about and their history, you'll find out that 客家 (Hakka) means guests = they did not originate from their current residence as they were displaced by conflict and strife in medieval China. Migrants/refugees generally don't seek to claim a slice of territory for their own, particularly in communalistic China, especially since provincial borders are mainly determined by geography (hence the many province names containing the direction markers of 东南西北, NSWE and also becoming the reason why large dialects e.g. Wu are spread across many provinces).
Although there were clashes recorded between the Hakka and the original inhabitants, nothing got too serious under the purview of the imperial government. The opposing groups still saw each other as Chinese and weren't questioning their right to live there but rather being protective of their own rights (think your younger brother getting mad for having to share a room with you so hordes his toys away). Expanding on the "extended family" situation, self determination/representation for each of the dialect groups was never really a common theme as they fully saw the government as their own (Chinese) and anyone could qualify to be an official if they passed the imperial examinations.
Fast forward to the modern era and today, each province's demographics has been screwed up beyond recognition in the face of urbanisation and industrialisation. Many can trace their ancestry to several groups and the overarching identity as a Han is more strong than ever. Many Hakka have also chose to emigrate overseas and when referring back to the homeland, they think of China as a whole.
Cultural assimilation and integration done right, if you ask me bois.
Sauce: have Hakka relatives and friends.
