That's really not accurate. Arma has a huge selection of upgrades and replacement parts probably just as many as Traxxas. The thing with the Arma is that you're not going to have to start out by spending extra money on upgrades.
https://www.rcplanet.com/traxxas-slash-short-course-4wd-rtr-tra68086-4/
good starter truck.
https://www.rcplanet.com/losi-1-10-tenacity-tt-pro-4wd-sct-brushless-rtr-with-smart-brenthel-los03019t1/
If your budget allows this is a much better truck