Arduino and Controlling a DMX Dimmer

I want to make an program to controll a dimmer of a lighning system. I want to write the program myself and because im a noob and I dont really want to use an easy USB-to-DMX-converter. I want to use arduino.

The problem is, that I heared multiple times, that you cant reach "the whole DMX Universe" with an DMX-shield.

So my question is: How suitable is Arduino, if you want to control DMX with it. The lighning system is not very complicated, just a dimmer and a few lights