the “purpose” of a rebbe is (as explained in tanya) he has a higher neshama and from him comes chayus – both spiritual and physical to his chassidim and even not his chassidim including even those that fight against him. this is only the rebbe’s relation to his chassidim, in essence the rebbe is much higher.
now as explained in tanya this hashpaah of the tzadik is even greater after he is nistalek, so whether you beleive the rebbe is alive or not ch”v, we have a rebbe, and thats where our chayus comes from.
i assume the intended question was that since some see things in chabad and breslev that they think is crazy, they should appoint a rebbe to straighten them out.
1) the reason they do these things (most) is because they are following their rebbe’s directive, so obviouly if there would be a nother rebbe he would follow the rebbe and not the opinion of some ywn coffee room person (or even a litvishe gadol). 2) and the ones that dont follow their rebbe, well if there was a live one why would they follow either, everyone beleives Hashem is chai vikayom, and many (r”l as of now) dont keep all mitzvos, halachos etc. 3) in lubavitch (dont know about breslev) the rebbe clearly said there wont be another rebbe, the rebbe gave instructions how to act when having a question after 3 tamuz, so should lubavith GO AGAINST their rebbe and apoint a nother one?! they would be misnagdim! not chassidim. 4) we cant give someone this neshama that a rebbe is, only hashem can 5) if youre question is someone to lead, we have rabbonim, roshai yeshivos, mashpiiim just like everyone else.
