I agree progress is difficult to judge sometimes, but one thing that starts to make things easy is brutal honesty with oneself.
Although splintering can lead to watered down stuff being peddled, sometimes it is not so simple as stuff being watered down or splintering but merely a limitation in conceptual understanding, teaching, training and evaluation methods.
Sometimes the splinter groups, by leaving the core institution, are less bound by traditional or institutionalized norms that prevent clear thinking and an honest approach to progress and evaluation. In the end they are the ones who aid in the overall development of the art by venturing into areas that may be seen as taboo by the core institution. It is difficult to generalize in these things imho.