The point of that was to show that a lot of TIME just went by.
That is VERY important, because TIME would be needed for the King of the Iron Islands to build his “largest fleet the world has ever known”. I believe that fleet will play an important role in the coming season.
How will Euron do that with very few trees on the Iron Islands?
The largest fleet the world will ever know is currently Dany’s sailing to Westeros. Thanks Uncle Euron! :)