The experience I've seen is that a Prophet has a mission to share with others what has been given Him rather than keeping silent...
When I said "better to keep silent than risk expulsion", I was not referring to the visionary or prophet. I was referring to the vast majority of those who join the religion created in the prophet's name where they join seeking truth and enlightenment, but the system does everything to discourage them from thinking for themselves and even challenging the prophet's teaching. The fear of expulsion is how they keep the system alive for its own sake. Not many are as compelled as the "prophets" to risk their own isolation or death for the sake of Truth.
But I agree that those who allow themselves to drink at will of that Water at their own risk do end up with this need to share. It's what happens when you move from deficiency needs into Abundance needs. There are of course other reasons why people "share" their religion which is not out of Abundance, but actually deficiency needs itself where they are seeking affirmation for themselves by getting others to convert to their points of view, and so forth. There is a subtle, yet pronounced difference between the two in where they begin from and end up.
Revelation is bestowed rarely and when given is sometimes a challenge to the established order and this can mean expulsion or death...
I'll put it this way. I believe it's not rare at all. It's freely available to all, at all times, irrespective of who you are. It's the infinite pool of Water from which we all drink in some portion everyday. But what is actually "rare" is those who feel so compelled as to abandon all else for the sake of it and to drink their fill. It is those who have overcome their own selves and all other voices as they give themselves over wholly to it.
Think of it in terms of Jesus' teaching of the sower and the seed. The seed (being "revelation" in this context) is freely scattered. But it only takes root and grows and survives on soil that is prepared to receive it. What is rare is a heart that is truly opened, and remains open. It is "bestowed" upon everyone and everything, like light streaming down from the sun. But not all are ready to receive it.
I personally think it is better to get away from the view that these who are are "chosen". We all are chosen. Not all of us however choose to receive. The "prophets" are just "you" in a different place with their lives. All the rest are myths we create about these people in order to have some object for your own faith to believe in, in the hopes you recognize it is in you already. The don't have the Answers, with a capital A. It doesn't work like that. Ultimately answers come from within each of us, unique to each of us. It's our own unfolding, not someone else's, that teaches us Truth.