Because I have read differently. I have read that when trying to lose weight, it is much better to each small meals very frequently in order to keep your metabolism running i.e. burning calories. You stop eating and your metabolism slows and will make it much more difficult to burn calories at rest.
Cardio(especially HIIT), weight lifting, eating the right foods, will speed up your metabolism no matter what. Now if you don't do any of that and just have a calorie deficit, then eating 6 small meals will help.
But in reality, the combination of lifting, cardio and healthy diet will promote faster metabolism.
It's really that easy to lose fat, everyone turns it into some big deal, when really all you need to do is refine your diet(eat healthy), have a calorie deficit.
lifting weights, doing cardio just helps the process go faster.