It's been known to be ineffective for a while, it's just that recently the FDA has admitted it.

I would imagine practically anyone who has tried taking it orally quickly became aware that it was not effective, and it has been available for years. I don't know that I've personally met a single person that found it effective, and the anecdote of having to register into "pre-crime" government databases to get the stuff that actually works is widely shared (in the USA).

It's been known to not do a whole lot for at least a decade, it just took until recently for the FDA to catch up and say "no you can't sell it".