Yes, without end caps, the dam will tear away from the wall when stepped on. The result for all collapsible dam designs will be water leakage in the corners, the location water typically cascades down the wall on all bathing fixtures.  If you have a dam with a hollow channel, this will harbor mold and bacteria where the seal has been compromised. Collapsible dam end caps are essential to provide a robust seal and a finished aesthetic that is easy to clean & maintain.