A lot of people have objections to oathbound material. (I am not, here, speaking of people who aren't comfortable with the idea and thus do not seek to get involved with religions that have secrecy vows, just as a note, but people who think that the practice is on some level intrinsically incorrect.) The objections I see most often are either that they have a right to possession of that information or that the information itself wishes to be free. I will respond to the first briefly, and the second whimsically.

Nobody has a "right" to that information. It comprises the private workings of groups of which not everyone is a member; it belongs to the members, who have made a commitment to keeping that information private. Much of it will not carry significant meaning without its proper context, for much the same reason that in-jokes depend on shared references and understandings. The followers of initiatory groups are no more obligated to share that information with non-members than any individual is obligated to share their sexual history, credit card numbers, or what happened on their ninth birthday with someone who just wants to know. They also have no more obligation to admit anyone who wants to get into their organisation than any individual has to allow anyone who wants to live with them under their roof. Their game, their ball, their rules.

Now, to the more interesting "information wants to be free" question.

Let us consider the possibility of personified information -- familiar to me as a Kemetic and thus one who works with the vital creative power of Words. This is information that acts, that desires, that wishes. Perhaps it is the vessel of the power of a god; perhaps it is a manifestation of the will of the universe; perhaps it is a thought-construct assembled in chaos magic. It doesn't matter. This information wants.

In the normal course of revelations from the divine, the universe, whatever, that process of satori: if the information wants into a mind, it will crawl in there and start gnawing on the frontal lobes all on its own. It will smack the conscious mind upside the protoplasm and bully its way into awareness. It will change the cognitive basis of the thoughtstream until it has a place to fit. This is what information that wants will do, and what it has done on occasion.

If the information has not clawed its way into someone's skull to lurk there like some sort of cranial xenomorph, it doesn't want in.

A lot of information does want in, mind, and doesn't do this sort of thing on its own. But a lot of this information that wants is constrained: it can only get in when the door for it is properly prepared. As soon as it has a space it can hop in, it leaps bodies as enthusiastically as a static jolt looking for a place to ground to. Under the right circumstances, understanding is nearly automatic: the information happens.

So how does one set up the right circumstances?

Often, by using proper juxtapositions of ideas and circumstances to create the charge that brings about that spark -- something which is most effectively done when the information about the event can be controlled to most effectively create the potential that will be electrified.

Which neatly brings things around to why initiatory groups tend to have oathbound material.