Novelty

I came across this novel fencing today, above Grasmere and near Loughrigg Terrace. I haven't seen it used anywhere else in the Lake District. Each tapered stake is driven through two horizontal slates that protrude from the stone wall, each slate having a circular hole in its centre.  Fencng wire is then strung between the upper parts of the stakes, which effectively raises the height of the stone wall. It's an elaborate, but very clever way of obtaining about another foot in height.  But why not simply build a little extra wall?

Am I missing something?