For the most part no, it's bad and will indeed hurt something. With a regular rack and pinion type slide, stepping on the cantilevered plywood in front can break the plastic guide across the front (I did it). If you have a Schwintek system, it will foul up the timing of the motors and computer big time. Then it may not close or open completely until it is re-timemd.
If my bedroom slide is all the way in the bed goes under the cabinet slightly. If I need to sleep in the bed I have moved the slide out a foot or so and slept there. Once it was because of the parking spot I was in. I frequently slide it out a foot to access drawers to pack,unpack. The front slide ,not so much. The front slide drops a bit once it starts to extend, I see no reason to avoid stepping on it when part way extended, it's a solid structure.