some popularizing reforms which reduced apparent coercion and cultishness cut membership by 75%
This seems like evidence against (a perhaps overstrong version of) the thesis of the OP, namely that cult “techniques” are ineffective. But note that
it’s perfectly consistent with them not being scarily effective; and
it’s also possible that these changes made no difference to (or even increased) the Moonies’ ability to acquire new members and keep them in the short term, and that it cut their membership because longstanding members who were used to the old way of doing things hated the reforms.
This seems like evidence against (a perhaps overstrong version of) the thesis of the OP, namely that cult “techniques” are ineffective. But note that
it’s perfectly consistent with them not being scarily effective; and
it’s also possible that these changes made no difference to (or even increased) the Moonies’ ability to acquire new members and keep them in the short term, and that it cut their membership because longstanding members who were used to the old way of doing things hated the reforms.