Well, one reason (as I’ve heard explained) is that if it’s all inside people, there is a great deal of room for rationalization and lying to oneself without anyone to check you. Also, with an institution, it concertizes divine reality much more than mere esoteric practice, and hence makes it more human … something we can relate to much more. Also, it brings one into community with others, whereas esoteric practices tend to segregate people, causing one to pay to much attention to the self. These are points of concern that rightly need attention. But why do you think that belonging to an institution is a prophylactic against self-lying? Have you taken any pew poles lately about practice/rationalization vs tenets of faith? Hmmm… Or read the news And “concertizing” is a wonderful term. Cement, solid, unyielding. Does that sound like living Love? and how does one “concretize” Divine Reality? Do you have God in a dogma box? Yes, churches can bring people into community. If that was the reason for religion I would recommend Mormonism. Have you ever examined the complexity of social interdependence in that institution? It is awesome! But ask me if I would become a Mormon!

For my part, esoteric practices, whatever you think they might be, are testable and pragmatic exercises in self observation, prayer, and community. Yes, community. Both the one I hold as my “extended family,” and each person I meet and interact with. And the self you speak of is not the Self that is the Source and End of esoteric practice.
Tell me something: If you knew in your heart that the “other” person in essence IS yourself, would you harm them? Would you abuse them? Would you lie to them? Would you steal from them? Would you do them any conceivable harm? Would you fulfill the dictum “Love thy neighbor as thySelf for the Love of me?” Who do you think that “me” in that case is?
I guess the keywords “pursued to the discovery of their root.” I’m not sure what you mean by “root” I think. Like, “ultimate cause?” Obviously God is the root and final cause of everything. So, I’m not quite sure what you’re saying. Where do your thoughts come from? where do they go? How is it that you know you think, or that you can make (if you can, lol!) dispassionate assessments of your own behavior as if you were observing someone else? What is the “I” of you before the acquisition of thoughts and memories that constitute what you call “me?” Why is it that the “me” of you changes constantly yet there is always “I” that doesn’t?
Even though Christ didn’t literally say, “Make all men Catholics” that doesn’t mean His words don’t carry the equivalent meaning. For what it’s worth, St. Ignatius of Antioch, a disciple of the Apostle John, shows in his writings that the term “Catholic” was already in use (and that was c. 100 AD). “Catholic” means Universal. What is the one thing that is already Universal among Humanity that is the possible doorway to going beyond the form of worship to its essence? Religion is always an external reference that attempts to persuade by arguments and sanctions and has God approachable through a medium. Why not go direct? Why do you think it has been a dictum through the ages to Know ThySelf? As I said, practice your religion for the interim if you like, but do it consciously.
*Faith is a “shadowy knowledge.” It does not provide us with the complete beatific vision, but it provides us with enough knowledge to love God and work for salvation.
Also, just because faith cannot be proved does not mean it’s not knowledge. Much of our natural knowledge cannot be proved, but it is no less knowledge. Mathematical axioms and first principles are intuited and cannot be proved. All reasoning depends on epistemic starting points that cannot be proved, otherwise they would not be starting points.* Of course all that is true. All knowledge is provisional. It goes as far as one is able to see, and it provides, in the case of religion, material that allows you tho think you are attempting salvation. But all such knowledge is, as I keep saying, contents. It is not Knowledge of Self.
All reasoning depends on epistemic starting points that cannot be proved, otherwise they would not be starting points. vs
Sorry to disappoint you, but how do we know that first principles and mathematical axioms are correct? We just know. No, we don’t know. We assume, and in our dimensions of experience these axioms are provisionally reliable. As Einstein said to the young man who asked him how he knew that “…that is a tree?” Einstein said “We have to assume something!”

But “I AM” is not an assumption, nor a thought, nor contents.
Physics and math can be proven from natural first principles. Christianity cannot. Not exoteric christianism. No.
- What? I’m sorry if I’m grossly misunderstanding you. * Don’t worry about misunderstanding me. That is completely unimportant. The question is, and always will be: Do you know yourSelf? Off to work. Blessings and Best!