Provenance
Where it comes from.
'Toy' appeared around 1300 meaning a trifle or a bit of sport, even amorous play, and only narrowed to 'an object for a child to play with' by the 1580s. Its origins are uncertain, but the sense of lighthearted fun has always been at its center.
'Daddy' is the childish, affectionate form of 'father,' and in informal speech 'the daddy' came to mean the top of a class, the biggest, the one in charge. Put in front of 'toy,' it turns a shop or a brand into the acknowledged head of the playroom.