Our philosophy with Trailforks, and a big reason why we've branched out to map all trail sports, not just mountain biking, is this: you can't just bury your head in the sand and hope people don't find trails, because they most likely will, especially with information being mapped on OpenStreetMap. Often trails are already mapped publicly on OpenStreetMap but often are mapped with wrong names and GPS tracks. Additionally, on OSM, you can't easily tell what activities are allowed on the trails, as they are just lines on a map.
The most effective way to avoid trail conflict and misuse is EDUCATION. You can't really blame a moto rider riding a MTB trail, or a mountain biker riding a hiking trail if there are no maps or signage telling them that they can't ride there.
By having ALL trails mapped on Trailforks, with proper tagging of what activities are allowed on each trail, the trail user now has easy access to information letting them know what they can and cannot ride. This puts the responsibility on the trail user to have proper education and resources before utilizing a trail.
On-trail signage is the most effective, but on-trail signage requires money, time and resources to create and implement. Updating maps on Trailforks is an easy way to properly label maps for the Trailforks community.
SAFETY
There are also safety reasons behind having trails mapped accurately and in having a complete map of a trail network. Properly labeled, tagged, and completed maps can help people navigate to safety if lost. If there is an accident, a good map goes a long way in describing the location to 911 or Search and Rescue members.
Search and Rescue teams can use the map to determine the most efficient way to an incident site and best way for extraction if needed.
This page lists many of the other benefits to mapping trails on Trailforks.