Even many adults don't learn the skill of having difficult conversations effectively.  Most people just want everyone else to be happy.  Certainly, no one modeled for me how to stay present even when conversations got uncomfortable.  It was so much easier to just give up or give in.  Now, of course, there are times when going with the flow is the name of the game, but if you want your kids to learn the balance between keeping the peace and learning to advocate for themselves in a constructive way, they are going to learn that much sooner if you teach it to them explicitly.