OSRS also has zero challenge yet that game has more players than RS3. The idea is to have a vanilla like experience that is constantly iterated on.
Crazy I wonder why people start to drop out of an experience after months that they’ve played dozens of times over! It’s almost like you do in fact need new content to keep people beyond engaged. Otherwise they end up fully quitting or switching to private server experiences like TWoW.
And dont use some idiotic “private servers are niche” audience. A private server is the reason classic exists, and TWoW itself has over 500,000 active players which is an insane amount of people for a private server.