If you are born before the year 2000, consoles such as gameboy, NES and Sega Gensis are not weird to you. In fact, you are still able to see such consoles around or even re-make and update some time back. You will undoubtedly feel nostalgia to play all those console games again. No problem plugging the old console to an old TV to play right?
Now if you are PS4 owner and you have that physical game disc like Witcher 3 and you remember you deleted the game some years back. Can you still experience the full game on your PS4 re-installing the game without connecting your PS4 to the internet?
Your answer at best is a "not really certain". Why? because you remember the whole game has update batches that are not found in your game disc along with all the DLC you have purchased on that game are up in PSN (that is if the game is still there offer by Sony).
Now you know why even if you own the game disc, you may not able to be able to play as a complete game like 10 years from now.
So what does that render you as a console owner? Feel our drift?