Muppet Stayman

3Club asks partner to describe their hand

Why does this version of Puppet Stayman reverse the meaning of the 3Heart and 3NT bids:

When Opener bids 3Heart to deny a 4 or 5 card major it gives Responder the room to show 5 spades. Responder would bid like this with 5 spades and 4 hearts or 5 spades and 3 hearts.