I think a lot of people will give a lot of answers to this, but the most lore friendly is probably the following.
It isn't. I mean, maybe telling all of humanity about anomalies would lead to a new age of prosperity. Maybe it would plunge earth into chaos. The Foundation doesn't know, and they don't care. Everyone at the facilities are told it is their moral, civic, and holy duty to secure all these anomalies secretly and, for the most part, they comply.
The Serpent's Hand believes differently. They very well may be right. After all, those opposing them do it either for financial gain, or out of some whack-job centuries old philosophy held up by a council of senile bureaucratic dictators.
Me personally, I stay more to the Serpent's Hand's side (Which may be obvious). The reasoning, and whether it's legitimate in most articles is left up to you.