PS2's dvd drive read speeds were awful, and there wasn't enough memory available to pull off something like this, even with PS2 quality assets at a low density
PS3 couldn't do it for the same reasons with PS3 quality assets at a low density
PS4 had a substantial increase in available memory, but would need to begin streaming data from its slow hard drive and storing it in memory well before arriving at a portal
PS5 can load a brand new environment with PS5 quality assets in a second or so during the portal transition