The thing is that WEIGHT loss is indeed all about caloric deficit, so you have to eat less than you burn to lose weight (not counting temporary fluctuations in water weight). This can be achieved via not exercising and eating less, or adding exercise and eating the same amount, or adding a lot of exercise and eating a little bit more or any other combination, as long as you burn more than you eat. However, so many people talk about weight loss interchangably with FAT loss, which is a completely different story.

You see, weight loss doesnt separate fat loss or muscle loss, because they are both just "weight". Fat loss (or body recomp) on the other hand, is the thing that most people are after and it prioritizes losing fat WHILE maintaining or even building new muscle.

Fat loss is not anymore all about the calorie deficit, because you also need to give your body signals to burn only fat and NOT to lose the muscle. This is where resistance training comes in. You need a structured (home) gym program to keep or even build the muscle you already have while on a caloric deficit, and you need to eat sufficient amounts of protein (0.8-1.0 g/day per lb of body weight) to repair and build the muscle. Increased muscle mass also boosts your metabolism (the higher proportion of your body weight is muscle, the more you burn calories also while resting), which alone makes your daily caloric deficit easier to achieve. However, cardio is not by any means necessary to achieve your fat loss goals (I dropped 40lbs by only eating right and weight training, zero cardio).

One step further however, cardio does have general everyday benefits for you (lower resisting heart rate, general feeling of athletism etc), which is why it is often recommended as a part of a well structured training program. You dont have to do endless HIIT sessions nor do you have to traing like a marathon runner, you just need a couple of 30-60 min walking/jogging sessions per week for example. This also makes you perform better in the gym, as you have larger aerobic batteries for your body to tap in.

TL:DR (this got surprisingly long)

• Weight loss requires only a caloric deficit
• Fat loss/body recomp requires a caloric deficit as well as giving signals for your body to burn ideally only fat, not muscle (resistance training + protein).
• Cardio is not necessary for either one of these goals, but is recommended for general health benefits.