Keto was originally used for therapeutic purposes which is where nutrient ratios came from. First and foremost, fat intake doesn’t impact ketone levels. There are no essential carbs, so that percentage could be zero. But carbs need to be kept low to stay in ketosis.  Protein needs should be based on lean body mass, not as a percentage of caloric intake. If one is consistently low on proteins, the body has another source, most of the time by breaking down muscle tissue. Now people are using it for weight loss/nutritional purposes. When we see these 'keto recipes' with nice-looking pictures of grilled chicken, steak, fish, shrimp, vegetables on side, maybe some cauliflower mash or vegan pasta, you wonder how much carbs you take for one meal.

Carbs determine ketosis, keep them under 20g net

Weight loss is driven by calories, not ketosis. For nutritional ketosis, "levels" of ketosis and ratios are both irrelevant. Too much protein is not a practical concern and will not kick you out of ketosis. Carbs determine ketosis, keep them under 20g net. Ketosis doesn’t control weight loss, caloric deficit does. Fat is incredibly satiating, so it can help people eat at a deficit more easily. What isn’t so easily identifiable is the impacts that chronically undereating protein causes. And keep in mind ketosis is caused by carb restriction, not fat intake. People who fast and eat zero calories end up in ketosis. Maybe a salad with a bunch of chicken in it or something. It's usually a healthy-looking plate with a standard protein and some vegetables. The excess protein concern is a non-issue for most people. So, all of these keto products you see in stores touting certain oils, aren't really on point if you're using keto for weight loss.

Ketosis is maintained by carb restriction, not by consuming a certain amount of fat

You don’t get into ketosis by eating fat, you get into ketosis by restricting carbs. There is no real need to restrict protein intake, since protein doesn’t kick you out of ketosis. That's a biological fact. Your liver starts producing ketones in the absence of dietary carbs. Ketone levels are irrelevant for weight loss purposes. Most products branded for "keto" are just looking to cash in by selling overpriced, unneeded supplements and labeling them as keto. Apart from electrolytes, there really isn't anything you need to supplement on keto. I personally take a few vitamins but nothing keto-specific. The reason for tracking macros (proteins, and carbs in overall percent) usually in grams and tracking them to make sure you get adequate protein to maintain and build muscle, and keep your carbs in check. When it comes to fats, you only need between 30 and 70g a day.

Different levels of ketosis, protein intake and gluconeogenesis

The primary concern over protein intake is a process called gluconeogenesis vs. glucose-new-creation, in which your body creates glucose that it needs.  There is no moderate or partial ketosis, ketosis state of metabolism is binary. There are varying level of ketones in your blood, but there is no varying levels of ketosis. You are either in ketosis or you are not in ketosis. The level of ketones in the blood is affected by fat intake, apparently, just not achieving the base level of nutritional ketosis. Some amino acids are able to be used in this process, but this process is demand driven, not supply driven. There are definitely different levels of ketosis, though, from nutritional ketosis to therapeutic ketosis. Protein can slightly affect ketone levels in people with certain medical conditions, but for the average person protein amount is not an issue.

Factors that make diet sustainable