Around 10 years ago I thought they were a terrible practice. A win for graphic designers that wanted simple and nice looking at the expense of usability.
But over time people learn and its standard. And as the NN group article points out: it has become familiar and known today.
My favorite iteration of this was in the This American Life mobile app that used a graphic of an actual hamburger instead of 3 stacked gray lines. This was also about 10 years ago I believe. Unfortunately I can't find any reference or graphic depicting it.