Hardware wise, that's been pretty much the case forever (example: Atari 5200 is a consolized Atari 400 computer), but it's that simplified interface and the instant gratification that makes the distinction between the two. On a game system: insert game. Press start. Play game. On a computer? Tons and tons and tons of loading and file management and updates and passwords and downloads and accepting EULAs and Oh God now it's crashed and I have to start the damn thing all over again.
Game consoles satisfy that urgent need for "ME GAME NOW." At least, they used to. In the olden times, you could start a game in the time it takes for you to drop a quarter in the machine and press 1P. Now, it seems like game companies do everything within their power to delay that dopamine fix on consoles... which is uncomfortably close to the gaming experience on computers. "Another cut scene? Gee, great. It's not like I started this video game to play a video game."