The million dollar question is: "Did you (w/your N=1) try the exact same calories as your keto diet, but then with more carbs?" No, you did not, and because it is hard to eat foods which adhere to the keto formula you lose weight on a keto diet.
What people also fail to mention with their anecdotal evidence is their age and gender. It is relevant because young bodies and brains are still growing, increasing calorie demand compared to a middle age adult.
> It really is the carbs and sugar that do you in, no matter how organic or home-cooked/homemade those carbs may be.
It really is the calories that do you in, no matter what type of calories or how you restrict yourself otherwise. All the diets are just some kind of abacadabra (or facade or placebo effect if you will) to make you focused on your calories intake, for example with specific rules about having to avoid certain products or ingredients which make it difficult to follow so that e.g. the subject cannot snack in between meals.
If you take in a lot less calories than the amount you require, you'll burn fat quicker. You'll lose weight quicker as well (although if you also start exercise, muscles weight more than fat). A lot more calories leads to building up fat quicker and gaining weight quicker. Both, eventually, until you are on the level of your calorie intake.
It furthermore also stands to reason that something with sugar is more difficult to limit than keto products because the former is more tastier. From an evolutionary PoV it makes sense because the sugar from fruits was a quick way to give us energy.
Furthermore, you should ask yourself whether the ingredients of the high carb food are needed. You'll find that you don't need them in the first place, possibly not in the amounts you eat them, but if you eat one cookie with the coffee in the evening that doesn't suddenly "ruin your health" because it is high on sugar. It doesn't "ruin your diet" either. The problem is that people cannot stick with one cookie in the evening with coffee. They snack far more, between meals. Yeah that adds up. Look on the packages and do the maths.
All the bad stuff is on the packages as well, very convenient: saturated fat, sugar, and salt. What a coincidence that our governments demand this being listed!