lol yeah, modded servers tend to do better than regulars.
1. Modded servers require admins/hosts with atleast some ability to run a server (atleast the person will know how to setup amxx and won't be confused on commands
2. People often get bored with standard CS
3. Theres not much reason for people to join a new server with little uniqueness and become regulars. If they do have 'favorites' they'll probably stick to those (unless they stop hosting). If they don't then they're the type who probably just go server to server.
4. Often those kind of 24/7 dust (or any 27/7 common map) become clones of one another.