I have no idea what the dab is, but I am guessing it is another one of today's trends, so yes it's overrated.
It's a stupid dance and routine people do after they say a joke/roast/or just something in general to make it funny. When it just looks cringe to me, it doesn't look that great and it's extremely simple. It's highly overrated.
I'm actually crying a little reading these posts because I'm the minority. I love dabbing, and my friends do too. At this point, it seems to be our own little thing.