Whether or not we should be do cardio before or after weight training is a question of priorities. If one is wishing to increase their cardio because their sport dictates the need for high cardiac output, then one wants to do cardio first. If one is doing training to lose weight and be fit then most likely cardio should be done after weight training. Engaging in cardio on a secondary basis insures adequate glycogen stores will be available to fuel intense weight training. Having burned available glycogen stores metabolic pathways will be more readily available for fatty acid oxidation, and losing body fat.
One always us to keep in mind what is the goal of one training. If you were training for sport you’re not trying to become a weightlifter or a bodybuilder if you are a bodybuilder you’re not training for sports performance. The glycogen that is needed to fuel intense training for sports is not the depleted glycogen levels one needs to prompt weight loss.
Training cam be general in it’s approach, or very specific depending on an individuals wants and needs.