Worry is one aspect of the carb problem. A diabetes diagnosis is worrying and can feel overwhelming for many. The whole 2 hour blood testing thing together with the news that, for example, brown rice is probably a little better than white rice but it might be better to avoid eating rice, most of the time, likely just adds to the worry and stress that comes with the diagnosis for many people. I think a lot depends on the kind of person you are. I find a lack of control worrying, whereas I take comfort and draw hope from taking action. Another person might just be completely overwhelmed and depressed by the whole thing, and that's definitely not a good outcome. Above all we have to live our lives and not let excessive worrying about food ruin it.
Another aspect of the carb problem and a big reason why the 'official' advice is the way it is, is fat. If you reduce carbs and make no other changes to your diet you will lose weight. While you have weight to lose that's fine, but eventually you have to get energy from somewhere or you'll waste away. That means eating more protein, more fat, or both. The 'official' advice is that eating more fat is bad for your heart, depending on the type of fat. Saturated fat like that found in dairy foods and red meat is cheap, tasty and full of calories, but a cardiologist would be horrified by the idea of swapping carbs for loads of cheese, full fat yogurt, cream in your coffee and fatty cuts of red meat, and doing that every day of the week. There is no agreement on what the 'healthiest', affordable low-carb diet is. You'll find a wide range of opinions on this forum and elsewhere about the best foods to eat in place of carbs. Until such time as there are extremely thorough, long-term scientific studies on the health advantages and disadvantages of different diet styles for type 2 diabetics, then the 'official' advice will probably remain the way it is and we will be left to our own devices as to how balance our diets.
Also, yes - carbonated zero sugar drinks are fine, at least they are for me. If there are no carbohydrates on the ingredients list (glucose, sugar AKA sucrose, high-fructose corn syrup etc.) then I see no reason why not.