Younger people have a lower ability to differentiate than older people. They had a lot of appropriate ideas but they don't always want to apply these ideas to the right people. If older people spend too much time with them during these years the young people tend to start to believe that their ideas are not correct and they start to suppress their desires. Once they have reached the stage where they understand about the right ways to express and enact their desires, how to start the right kinds of relationships that are required for the different types of desires then it becomes safe for older people to participate more without fear of squelching their creativity.
Its not just a matter of being tolerant for the older people, as that would also teach wrong behavior, but the real reason tolerance isn't an option is because it isn't possible.
It can be tough to start up a system of refusing to interact with people unless they show the right degree and expressions of respect and to set up a system to train those who don't. The demands of individuals for the time and behavior of others differ due to status and activities so learning directly from another master isn't always the most desired option. Once you get to a certain level though it is fun to interact and assist as an honored visitor and exchanges of products can be possible.
