Its hardly was a secret before. And avoiding mentioned on forums won't stop FDev mission generator changes long in production & testing already. FDev has lot of stats in database and they know exactly when some players earn income in top percentile - so they immediately can drill to logs and see where it comes from.
They usually prepare to cull sources of "get rich quickly" before it has a chance of blowing up - since development cycle actually takes long time.
Look at rhea, it's been a place to get lots of credits for a long time, it just got popular and a mass amount of people milked it look how quickly it got nerfed. Yea people have their little place's they earn a good amount of credits and you're right fdev does know, but if not a huge amount of people know about it fdev doesn't seem to mind. Only when thousands of players suddenly head to a cash cow then fdev takes action.