Heavy vehicles can damage wet or soft backroads. Huge ruts created by a careless 4x4 may make the road impassable, encouraging others to bypass the obstruction, thus creating ghost roads. Driving through deep mud isn't macho, it's mindless. Streams Are Not Roads. Don't drive in streams.
All bodies of water contain extremely delicate ecosystems.
Use bridges or cross at designated fording points. Avoid Excessive Wheel Spin. Many designated backroads are soft and can be damaged by excessive wheel spin. Carefully crawling over a tough spot, or using a winch, is more effective and easier on the equipment than trying to power your way through. Spinning tires just to spin tires is mindless.