I use Reeder to read blogs I follow. You navigate from article to article with the arrow keys which are on the right hand side of the keyboard. I am left-handed so even though I wish the keys were on the left, they are never going to be.
In comes TouchBar and the app developers can now do cool things like put up/down arrows on the left side of the bar. It is a little detail but it is nice to have actual arrows on the left side.