Hey OP, Z threaded rods are never 100% stright (like smooth rods should be) and making these nuts loose can help against binding, so yeah it is true, but check few things before you do that:

1. Clean threaded rods and relube with grease, also clean your smooth rods and relube with sewing oil (should be done once a month or 2)
2. Have you added bearings on top of the treaded rods? Lot of people do that and its wrong! (Top corners are cropped out of the photo) It can overconstrain Z axis and cause binding, so remove bearings if you added them, top side of threaded rods should be free
3. Remove threaded rods and roll them over flat surface like glass. Its easy to tell if they are bent and if they are try to strighten them a bit. Also inspect rods and nuts for any damage. Edit: your threaded rods are part of motor assembly so this step might be more difficult
4. Remove threaded rods (or nuts) and move X gantry up and down with your hands and make sure everything is moving smoothly and also make sure nut position is aligned with Z motor axis. If its not aligned you should adjust frame (loose screws, make everything perpendicular/parallel and thighten again). Z motor axis must be parallel to smooth rods and both should be parallel to each other (check motor brackets, try loosing motor screws and align it better)

If threaded rod is bent you can loose threaded nut to avoid binding, but it would be better to replace the rod (or motor). Some level of bent rod is acceptable, but too much will cause issues like this

How long do you own this printer? Have you got it used or new? Was it printing fine before?