What you describe is a limit of the format of the written word. The limitation is that the word is written, then read. It cannot be written while being read.
Readers will only read if it provides value to their life. In fact, it must provide enough value to warrant the expenditure of energy reading it. If a story has things like conflict in it, it is easy for the reader to wedge their own conflicts against the story's conflicts, and gain happiness as the story resolves its conflicts (and possibly gives the reader a hint or two about how to deal with their own conflicts).
Jumping all the way to "no conflict" is quite a step. Let's instead look at how we could possible keep a story interesting with less conflict. With less conflict, there is less for the reader to attach their own conflicts to. Thus, to retain interest, the book needs to strike closer to home. The conflicts that do exist need to be more and more pertinent to the reader's daily conflicts. Without conflict, all a book can do is resonate with one's current state. There's strong value to this, but part of the human condition is the desire to change states, and eventually the book will fall behind.
So how do you continue to be more and more pertinent? Well, this is where the limits in understanding the reader come into play. Great writers know their audience well, but no writer ever knows their audience perfectly. At some point, the only way to write a more interesting book is to wait for the reader to get through the first chapter, then observe their mental state and quickly write the second.
There is a storytelling medium which can circumvent this. A story which is spoken or acted can bring the audience into the story, allowing the story to be tailored closer and closer to themselves as the story unfolds, freeing them from the need to make conflict to sell the story.
The only way to make an interesting story without conflict is simply to go out and be that story! There's lots of interesting people out there. I wonder how many of them are telling such a story.