Why would anyone choose to "kill two birds with one stone" when he/she can bake two cakes in one oven?

The English saying appears to originate in the 1600s ... and it was initially used in a somewhat pejorative way, to describe a philosopher’s attempt to prove two arguments with a single solution. The implication was that killing two birds at one time is extremely challenging and unlikely, and that the philosopher’s attempt should be viewed with extreme suspicion. The philosopher had obviously failed to satisfy his critics, who suggested that his attempt was about as successful as a try to knock out two birds with a single stone.

The Chinese had similar sayings "one stone two birds" and "one arrow double vultures" ... but there is no evidence those are the origin of the English saying.

Some claim it came from the Greek Mythology tale of Daedalus and Icarus.  Daedalus devises a plan to throw stones at the birds in the hope of fashioning artificial wings to enable the pair to fly home.  But there is no mention how Icarus got the feathers for the wings.