Because catching on fire is a serious thing. Just ask Ferrari.
Late last month it was first revealed that Porsche had recalled its new 911 GT3 due to the possibility of it catching on fire. In fact, the German automaker had previously halted sales and deliveries of its fastest and most powerful model until it figured out the exact problem(s). Porsche still hasn’t revealed the cause, though it's rumored engineers have figured out the problem. A company spokesman only stated that there is "no update from the factory," but it's only a matter of time until we have answers.
“Given the high performance nature of the engine and sophisticated componentry and engineering, it's a situation where you have to evaluate every situation to the minute level to make sure you don't miss anything," according to the official. Fortunately, there have been no injuries or fatalities and the problem remains solely with the GT3 and no other model. "The thresholds in that engine are a lot higher for performance but the tolerances are much lower, and given we are an engineering company that prides itself on the reputation we are not going to take any risks," the official concluded. GT3 customers have also reportedly been "quite understanding" of the situation and are "prepared to be patient" until the issue is fully resolved.