There is nothing wrong with a martingale as a working collar. It is classified as a type of limited slip collar. When you attach your leash to the ring in the center of the chain, and pull on the leash, the collar will tighten, similar to a slip collar (sometimes called a choke collar). The difference is the slip collar can close down to nothing, and the martingale or limited slip collar can only close so far before it turns into a regular buckle type collar. When the collar is adjusted correctly, the two side rings touch when the collar is snug but not strangling the dog. That is the tightest the collar can become when you pull on the leash
Why a martingale with a chain insertion? The sound. When the links of the chain run through the metal side rings, it makes a distinctive zhing sound. During training with either a chain slip collar or a prong collar, that sound becomes conditioned as a correction. The sound alone can correct a dog, even if the collar correction does not follow. Dogs trained on a prong collar will often take a correction from just the sound of the collar being shaken, so if you need to tune something, you don't even have to put the collar on to do the tuning.
Martingales have an additional purpose, not related to training or corrections. Because the collar becomes smaller when the leash is pulled, it is very difficult for a dog to back out of a martingale collar. In that way, a martingale collar is safer than a plain buckle collar because the dog is less likely to get loose from it.
Your program may have issued that collar for either or both reasons.
Working collars include the buckle collar, the martingale, and the slip collar. Prong collars, head halters, illusion collars and the like are training collars. A training collar should be used temporarily, not as a way of life because there is no need for them on a trained dog.