OpenStreetMap data is created by volunteers just like how Wikipedia content is created by volunteers. However when the public are involved, issues can occur such as bias and even censorship.
Political borders can be disputed weather there is a way going on between two nations or not. Who decides what the border is on OpenStreetMap? Perhaps a business owner adds their business on the map but many other contributors band together to remove the business on the map.
I would like to suggest a few features to address this.
Master Maps & Plugin Maps
If you played an Elder Scrolls or Fallout game on PC and used mods, you will be familiar with master files and plugin files. Master files (.esm) files are considered layer 1 of the game data while plugin files (.esp) are layer 2 of the game data. The game studio creates the master files while modders can create plugin files. Plugin files will require one or more master files.
I would like to suggest a similar option to be included for OpenStreetMap. The OpenStreetMap data would be a master map, layer 1. However anyone else can create a master map or plugin map that is built on top of the OpenStreetMap data or any other master map.
A map that requires other master maps, will not be a copy of the map, but will save the changes it has made from the master map. These changes can include anything it has added, edited or removed from the master maps it requires.
The only master map that OpenStreetMap will host is its own master map. All other master maps and plugin maps will have to be hosted by others.
Repositories
Just like package repositories for software on Linux or F-Droid for Android, to create an self hostable, open source repository for maps.
The official repository would be official master map of OpenStreetMap, however to be able to easily setup your own OpenStreetMap repo that host its own master maps and plugin maps.
To allow users to signup to any of these repositories if the host allows user registration and allow users to request changes to the maps on the repository.
I would also like to suggest the option to hosting map data using Bittorrent. This can allow users from all over the world to download and seed the map data globally, helping reduce bandwidth costs for OpenStreetMap and all 3rd party repos and allowing the world to easily store the map data in a decentralised way!
Conclusion
OpenStreetMap is an amazing project. However it is still very centralized in its data. No need to create a blockchain or a cryptocurrency to solve this issue. Simply the ability to spin off your own maps and be able to modify the map outside of the official OpenStreetMap repo and be able to host your own maps will be all that is needed to make OpenStreetMap true decentralized.