The majority of GTA 5 mapping today is done with FiveM in mind. Singleplayer mapping isn't dead, but it's a smaller scene. Let's break down why.

How FiveM ships maps

Servers bundle the map with their resources. When players join, they download it automatically. There's no need to install anything. The map only exists for the player while they're on that server.

This allows maps to be ephemeral in a positive sense - servers can update and replace maps without players needing to take any action.

How singleplayer ships maps

The player downloads a map mod and installs it. The map stays installed. Mods can conflict with each other. Updating is manual.

More friction, longer-lasting effects, smaller percentage of users who would install.