What doomed secular hedonism was the point when it closed the loop (a point which secularism was, intrinsically, bound to reach) - so that it became legitimate to influence feedback, so that it became acceptable to shape outputs as well as - and at the same time as - inputs.
So long as human nature was accepted as a given - then secular hedonism was limited to giving people what they wanted. But when human nature became regarded as a product of culture, it (apparently) became legitimate to change what people wanted, or change people so that they wanted what they already had - or what you were offering them.
Then is madness - a system that is simultaneously gratifying wants, creating wants, obliterating wants and amplifying wants.
How could this kind of system possibly be evaluated? It is merely an elaborate and obfuscated process of self-justification.
Democracy worked reasonably well when it was a matter of recording voters preferences; but when it became possible to change voters preferences and choices, and to change the composition of the voters - then it became insane.
Science worked reasonably well when scientists tried to provide obviously useful breakthroughs; but when it became possible to persuade non-scientists that 'whatever scientists have done' constitutes a breakthrough, and when success in science was to be judged by evaluation systems conducted by successful scientists (viz. peer review) - then we are in the realms of insanity.
When the feedback loop has been closed, then we are in the realms of insanity; with outputs and inputs, claims and counter-claims, whirling and spraying-out centrifugally; with no baseline for evaluation of success or failure.
Temporary states of rest coming only from the coercive imposition of an 'official line' on what has happened, is happening.
Just an endless propaganda war trying to convince people of this or that - with nothing deeper or permanent than whether people - here and now, contingently, irrationally, apparently - acquiesce.