Depending on timing, the athlete’s needs, and how much versus how much of everything else, carbohydrates land anywhere between “counterproductive” and “necessary.” But they aren’t bad. They have a specific set of roles, most of which are easily fed from stored fat.
In a very long study (3 years ish), those who ate fewer carbs ended up burning about 250 more calories per day: https://www.bmj.com/content/363/bmj.k4583
The authors note that were this to continue trending, participants would lose 20lbs while eating as many calories as their higher carb-intake counterparts. REREAD that.
This makes sense, given lots of known physiological phenomena. Take note, the difference in calorie burn between low carb participants and higher carb was an average of over 400 calories if the higher carb people had any amount of insulin resistance. That is, if you are prediabetic, you burn 400 MORE calories per day eating the exact same caloric intake but from fewer carbs. You burn more calories with the exact same activity and calorie intake when less of the food is from carbs.
Again, this is why the alleged or ostensible caloric content of food and the alleged or ostensible caloric expenditure from activity do not constitute a sufficient explanatory model in human biology. Gasoline has calories. Bleach has calories. What our body does is more nuanced than simpleton calorie thinking.