Until someone bucks the trend and does it.
But for that you need someone with actual intelligence and empathy; a Feynman of that sphere so to speak.
In every gatekeeper community this is the order of things until someone finally destroys the gates to the knowledge and the monopoly of the priesthood. Until then, it's basically "blame the victim" for their own lack of understanding (e.g. "people listen very little", "people are more skeptical of others", "they try to poke holes in your explanations", "They'll repeat whatever objections they've seen or heard somewhere", etc).
Hopefully people who read QED don't go around thinking that they know all they need to know to make an informed judgement about lagrangian QM.
And regardless of where we place the blame, at the end of the day:
> In life, there are a lot of obvious things that are very difficult to teach.
Yes, in theory.
In practice, people come to your explanation pre-conditioned with a lot of (often politicized) misinformation, Dunning-Kruger type overconfidence in their own ability, very little curiosity or openness to new ideas, and exhibit the attention span of a 26th percentile squirrel.
People tend to listen very little and are more skeptical of others than they are of their own understanding: instead of searching for ways in which their mental models need adjusting, they try to poke holes in your explanations. This undermines both "ELI5" approaches (because what you gain in simplicity you lose in nuance and correctness) and more pedantic approaches (which require more prerequisite knowledge, experience, and patience).
If you disagree with me because that is not your experience, just consider that you probably surround yourself with above-average intelligence people.