That just isn't true. There is a separation between the front and back lines of the defense. If they aren't extending at all, it means that they arent in front of the offensive player and he is free to attack that gap. If they are rotating to stay in front of the guy to prevent that drive, then the rotation leaves room for ball movement to open seams. If they aren't rotating in front of the wings, then they're stupid to be in a 3-2 unless they're trapping from it. Against us, it works because we don't flash to the center or post hard the block. We like to pass back and forth.
If the gutman is fronting the post, how is he keeping the flasher from killing the defense. He can't do all of that and that's the weakness in the D. The middle of the floor will kill a 3-2. A base 1-4 all low offense would be indefensible for a non extended 3-2. PG is free to roam and drop the ball to an overloaded baseline with far post rolling through the center and far baseline going to the opening left by the vacating big.
The 2-3 doesn't share that weakness, but can't guard the floor. Teams packing it on us will be in the 2-3.