I felt that when italics were created, someone or a group had to decide whether they wanted it to lean to the right or left. I'm guessing they were right-handed.
Well, in that case, I shall agree with you when you say italics were not invented by computers. So if italics were invented centuries ago historically, then they would have been suggested by right-handed people I guess.
And yes, lean to the right/left is a better word than shift (my bad).