Did you mean weight loss instead of fat loss perhaps?

By "fat," most people mean subcutaneous adipose tissue, and isn't that the weight we seek most to lose? To what other fat might they refer? Intracranial lipomas?

Resistance training is fine for fat loss, at least up to some level (single digit numbers usually need more). It's just that muscles are heavier but muscles consume more energy (colloquially said).

That's why I thought that perhaps it was weight loss as in scale measurement that might be the concern.

but claiming exercise is good for fat loss is big business, so everybody believes it.