I first heard about this a few years ago when DD was living in Dubai, parents had cute photos of baby 'smashing' first birthday cake by professional photographers, who advertised their services for the event. Not something our DGC have taken part in, but babies can make a mess when eating cake, so think its a current fashion aided by social media.
DGD has messy afternoon play at her nursery in this country and loves them, they include cake, paint, mud and all the things you would not want thrown about inside at home,