First of all, main and only principal of weightloss is calorie deficit.

The CICO model describes what happened, not why it happened. There are more clinically useful models such as the carbohydrate insulin model.

Lack of carbs (primary source of energy for humans)

We run on fat when we are born, when we sleep, when we skip a meal. Glucose is metabolized before fat because it causes damage if it lounges around. i.e. Alcohol is burned before glucose but we don't claim we are adapted to alcohol.

makes weightloss harder because someone on keto would feel less energetic for quite some time due to at least adaptation to said metabolic proccesses.

1-4 weeks is the typical fat adaptation period, and if people maintain their electrolytes they don't have any lower energy levels.

In general, forcing organism to get energy from some less efficient and not-quite-as-good metabolic transformation

Less efficient is a new one to me? What is less efficient to burning fat? We store fat on the body, the entire point of weight loss is to burn fat - we should encourage people to be in a fat burning metabolism if they want to lose weight.

is something that comes from a belief rather than reason.

Belief? The data and the models make predictions people can measure themselves in a few weeks, it is very empirical.

I don’t mean that one can’t lose weight on keto.

If you know keto works, why do you call it a belief without reason?

But it does increase discomfort during weightloss which increases the chances of giving up on it.

I'll agree with you here. Staying on keto means beating carbohydrate addiction. Addiction is strong! However, it is worth the cost of admission - People should be doing keto to get healthy not to lose weight i.e. Don't lose weight to get healthy, get healthy to lose weight.