Games must enter an interactive state that accepts player input within 20 seconds after the initial start-up sequence. If an animation or cinematic shown during the start-up sequence runs longer than 20 seconds, it must be skippable using the START button.
What earlier games were doing was very similar, but was done for different reasons. Arcade games had an attract mode that would show gameplay or intro cutscenes in a loop when the device wasn’t in active use and had an “Insert Coin” flashing to attract players. The normal game would only started once coin got inserted into the arcade machine. Early console games had that attract mode too, just “insert coin” replaced with a “press start”.
What makes the modern start screen different is that there is often no cutscene to skip, no gameplay to watch, it’s just a pointless screen before you go to the main menu.