This question already has an answer here:
The concept of "Lo Tisgodedu" is homiletically interpreted to "lo ta'asu agudos agudos" - do not make distinct groups. This is used in a variety of places, most notably in the principal that one does not publicly deviate from minhag hamakom.
As discussed elsewhere, this doesn't seem to impede the creation of local/regional minhagim. What is the "upper bound" to the implementation of this concept, and how do we resolve conflicting minhagim within a pluralistic group with no minhag hamakom (Rav Moshe, IIRC, claims that the US is such a situation)?