Bravo Sierra! The only way you can learn about being married, truly, is to be married, or to have been married. Take what you're saying and apply it to the secular world: What you're saying, more or less, could be applied to psychiatrists---they should "know more" about the human condition because people spill their guts to them.
Yet we all know pyschiatrists are often most in need of psychiatry themselves. If you trust a psychiatrist to govern your heart, or give you sound, solid, unbiased advice about what's best for you, let me know---you might be interested in purchasing the deed to the Zakim Bridge from me.
Also, psychiatrists only talk to the critical cases - it costs money to see a shrink, but the priest is always there for everybody, the untroubled, the mildly troubled, and the very troubled.
The idea that you can only learn about marriage by being married is the same thinking that promotes the idea that only black people can understand "black issues", only women can understand how women think, etc. and nobody else is qualified to have an opinion or voice one. It flies in the face of the universality of the human condition.
And I wonder how many married couples have actually thought in depth about the transcendental meaning of marriage, as the late Pope John Paul the Great did in his masterful study of the theology of the body . . .