Well, you have arrived at a very reasonable conclusion and I would be surprised to see anyone argue otherwise.
I see. Why would you ever limit your diet like that?
I would love to help but, sadly, I cannot afford the time. I you are really interested then I would probably advise heading to https://scholar.google.co.uk and starting your research there. I have no idea what your circumstances are, of course, and thus what particular goal or goals you would like to achieve by changing your diet or lifestyle, but in order to make it easy for you to start your journey, I quickly found the following papers that I thought might interest you:
https://www.sciencedirect.com/science/article/pii/S1933721309000099
I hope this will help you get started.
It is true that ingesting too much protein can put you out of ketosis (most of the 20 amino acids can be used as substrates in gluconeogenesis) but it is not a problem since any well-composed ketogenic diet does include adequate levels of protein. I can see no “serious trouble” related to that unless you are talking about improperly designed diets but then it is not really relevant to our topic as it is not specific to LCHF (e.g. one could be on a low-fat, high-carbohydrate diet deficient in protein). In general, malnutrition is rare in the developed world. Protein is rarely a problem irrespective of one’s diet and activity level.