Yaerb, it’s not that they say that all life’s answers can be found in rav nachmans seforim. They believe in hiskashrus, but not in the heretical, rebbe-save-me davening to rebbe stuff.
Rather, they believe that when one connects their neshoma to the neshoma of a tzadik through learning his seforim, they are given wisdom and insight into their lives and their issues.
It’s also chutzpah to just dismiss a mahalach and a mesorah off the cuff like that without giving it any analysis or even reading their seforim. Breslov is recognized as a legitimate branch of chasidus, and is wildly successful in helping peolle who feel that they are enslaved to their yatzer hora. Not only that, rav nachmans insights into psychology were so profound and ahead of their time, that a leading Israeli psychologist said that rav nachman was the world’s greatest therapist!
With my talmidim, many times i can identify and give them advice based on what I’ve learned in likutei moharan and other seforim – BUT they’re complicated and you need someone level headed to explain them to you. I had one such person in yeshiva. Rav yaakov neir shcechter is another such example, recognized by the eidah charedis and the world in general as a big tzadik and talmid chacham.
You’d be surprised at how many times I’ve seen a kid change behaviors when he hears a vort from rav nachman; I’m not talking heavenly, lofty ideas; lots of what he and rav nosson write is down to earth. Things about taking it day by day, not being meyaesh…but with depth and meaning, not trite cliches.
As for how their mesorah is passed down, they had rabbonim and manhigin, but none would assume the position of rebbe or have chidushim.