It is regrettable that no data was transmitted during descent or landing, putting engineers in the position of trying to reconstruct an airplane accident without the black box. Hardware failures at the time of separation from the cruise ring could explain the loss of all three spacecraft. So could some bizarre or very hostile surface on the polar terrain, different than expected by scientists. The Deep Space 2 penetrators are known to have landed near or at the edge of a crater. This was a high risk mission and perhaps they hit rocks.
Speculation now is rampant and endless and without data it is impossible to resolve.
Getting some data from the imaging camera on Mars Global Surveyor is a long shot. The camera can resolve objects just about as big as the spacecraft. Maybe something can be seen if and when it flies over the landing site and takes pictures. But that is right at the edge of possibility. The 2001 Mars Surveyor mission uses much of the same hardware and descent propulsion system as did the Mars Polar Lander.