Within almost every chassidus you will find those who are makpid to marry davka within their chassidus, and those who have different priorities in shidduchim. I know such people in Belz, Skvere, Satmar, Viznitz, Bobov, and Pupa.
Many times these families are extremely involved in the chassidus (davening strictly in the Rebbe’s shul, attending every tish and rebbishe simcha…). It’s hard to imagine an “outsider” integrating into such a family when life is centered around the Rebbe, the shul, the mosod, etc. It only makes sense that they stick to their own crowd.