The match that lead to the change iirc that was West Germany beating Austria 1-0 at 1982 World Cup, thereby ensuring both teams went through at the expense of Algeria aka "The Disgrace of Gijon" as the teams were so blatant about it in second half.Isn't that the reason for the last round of games been played at the same time , to stop teams playing for a draw.
Draws might get a team through but finishing top gets a 'better' next round game than finishing second or third..
Ireland v Netherlands in Italia '90, hearing England were beating Egypt 1-0 and a draw was enough to send both teams through, dialled down the intensity.
With potentially three teams getting out of a group now, you have more situations where a draw sends a team through, and there's no real advantage to being 2nd over 3rd.