I'll note that it took centuries for smoking to go out of style (it still isn't in many developed countries) and it took decades for most people to "consider it toxic" even after there was scientific evidence to corroborate it.
It's arguable that Facebook will be in an even better position to fend off accusations of its toxicity since Facebook has one of the world's largest human sociological experimentation platforms ever known to man. They are able to run experiments and gather evidence that economists have not otherwise been able to run.
I'll note that it took centuries for smoking to go out of style (it still isn't in many developed countries) and it took decades for most people to "consider it toxic" even after there was scientific evidence to corroborate it.
It's arguable that Facebook will be in an even better position to fend off accusations of its toxicity since Facebook has one of the world's largest human sociological experimentation platforms ever known to man. They are able to run experiments and gather evidence that economists have not otherwise been able to run.