Hmmmm. . . there was no mesorah for chassidus, was there. All those changes to nusach, shechina, glatt, mysticism, rebbes, new rituals, ect, ect, ect. It was a movement to change the way Judaism was practiced because many of the masses had emotional/spiritual needs that were not being met by what was then the “traditional” way. The traditionalists fought against it and even called its proponents kofrim and reformists. In the end, the criticism tempered the changes, the positive impact of the changes tempered the critics, and both sides recognized that they could both exist within the bounds of halacha.
Sound familiar?
. . . and the wheel, it keeps on a turnin’.
And sometimes the opposite happens. Conservative started as an ostensibly halachic movement also. And after some time everyone saw what it is.
So what do you think makes some movements be accepted, and some movements just go further and further until they are totally cut off?