CMOD Project

Hello experts,

i have small question regarding Customer Exit,

for implementing the exit generally we'll be creating Project in COMD tcode my question is in that project we are writing the code inside INCLUDE PROGRAM

so in that case we can directly write a code in the include program and move it further without creating any project. so why do we need to create any project what is the main purpose of creating project.....

thank you all in advance 😊............