Ah come on, when someone says this everyone knows what is meant and that when it happens there's a risk you could end up with a prime minister who is popular within the party but disliked by the electorate (Gordon Brown or Liz Truss).

So yeah you don't vote for a PM ... but there's a clear, well-understood difference between being the leader when your party wins the general election and a winning an internal leadership battle when a few hundred thousand party members vote.