With regards to not eating carbs to lose fat and the methods of various coaches. Very briefly let’s look at how macronutrients are utilized. Upon ingestion a macronutrient will encounter one of two fates, either it is oxidized to meet fuel demands or it is stored for later use. Protein is a bit of a special case and is a bit too complicated to really get into here so if you’re interested we can tackle that later. Carbs are the bodies preferred fuel source (i.e. glucose) and will preferentially be oxidized to meet energy demands. Once these demands are met, excess carbs are stored in the liver and/or muscle as glycogen.
The fact that people like to claim that carbs are “unnecessary” simply because they do not compose the structural components of cells is a bit short-sighted and simplistic given the overwhelming efficiency of carb utilization for fuel. It is rather obvious what the body would prefer regardless of whether it is absolutely “necessary”. But I digress. Carbs will not be converted to fat under most circumstances as the enzymatic pathways are terribly inefficient in humans. You can overcome this at high intakes however (i.e. >600g per day for a 70kg man) Now, the utilization of carbs as energy will “spare” the other two macronutrients the fate of oxidation. I’ll come back to this in a moment to tie it all together.
Fat, on the other hand, is very easily stored via direct mechanisms and will only be used for fuel if absolutely necessary. Insulin is NOT required for this to occur. You can see that if you eat a bunch of carbs AND fat that what will happen is that the carbs will be used to meet energy requirements and the fat will be left free to be stored with almost 100% efficiency. Now if you cut carbs you will necessarily lower calorie intake to the point that energy demands are not met with carbs alone and fat must be used to make up the difference. No magic here. You could just as easily lower fat to decrease calories below maintenance and even though carbs are being used for energy stored bodyfat will still be used to make up the difference (it has to come from somewhere, remember thermodynamics).
So I hope you can see that just by dropping out carbs (which will make the body use fat as fuel) but eating all the fat you want will not magically cause greater fat loss than a low fat diet could. Now are there benefits to low carbing it? In certain respects yes. Insulin does halt lipolysis. Now in the face of a hypocaloric diet this is not that significant but if you were going for fat loss at all cost (i.e. the last lb of bodyfat before getting on stage) then a low or no carb diet might help you do that by blunting insulin as far as is possible. So that sounds pretty good right? Well yes, but remember that biology is a zero sum game and gaining an advantage in one area leads to a loss in another. Insulin is anticatabolic to muscle (again mechs are too long to go into) and glycogen is also muscle sparing via several pathways. So cutting carbs makes retaining muscle a very hard thing to do during a diet (this has been born out in practice for decades in the natural lifter).
Try gaining muscle on a low carb diet vs a moderate carb diet and see for yourself how significant the difference is. The same tricks that build muscle are the same that preserve muscle. This is why so many bodybuilders using a low carb diet for the duration of their prep find holding muscle so difficult.
Again, there are million roads to Rome, albeit that some may be a little straighter. Shelby, Hight, and plenty of others use carb cycling in their plans (and hopefully with the primer above you can see that it could serve as a stop gap during either a cut or bulk (2 steps forward, 1 step back)) and it would work perfectly well if calories were below maintenance. However, there are plenty of examples of coaches who do not do this and get natural (this is KEY) athletes in ridiculous condition using moderate carbs and lower fat approaches i.e. Norton, Thibs (see the Daryl Gee project for more), Jeff Willet, Skip La Cour, etc. There are examples of guys using no carbs too but I think you can see the big picture. It all works.
Once the energy intake has been addressed (calories are below maintenance) then the rest is minutia and doesn’t become important until you are getting advanced enough to get on stage. I hope this is coherent enough to follow. I have so much more to say on the subject that I could probably write all night to clarify and elaborate on some of this but this is already stupid long. Bottom line…
Pick your poison. You can find examples in all camps so using the argument from authority is a failing proposition.
Otherwise you are right on track.