Why I think high carbohydrate intake is detrimental to strength

First off let's start with the facts. Any carbohydrate intake leads to an increase in insulin levels in the blood. The insulin is there to shuttle the blood glucose from the ingestion of carbohydrate into muscles and the liver.  This influx of massive insulin surges that accompany heavy carbohydrate intake also lowers blood glucose levels to a starvation mode level.

When the body has low blood glucose levels it first starts breaking down muscle tissue and starts feeding on muscle glycogen reserves and then switches to fat reserves for energy. The problem with this system is the attack on the muscles.

As a person who trains for strength, you need all the muscle you can get. Why would you start that insulin effect of breaking down muscle for energy supply to the body no matter how temporary it lasts?

I used to believe that more insulin is good because you need it to produce Insulin Growth Factor, an anabolic hormone your body produces to stimulate muscle growth.  The problem is that insulin also lowers blood sugar levels and shifts your body into starvation mode.  What happens when you go hungry?  Your body becomes catabolic and breaks down muscle for however short a time to return blood glucose levels back to normal.

One or a couple more times of this small stealing from your muscle might not add up to much. But cumulatively over the course of three or four rest days between workouts with several carbohydrate feedings done each day, those small catabolic attacks on your muscles can add up to significant strength loss.

I hate to beat a dead horse, but the fact of the matter is the ketogenic diet has as its goal to never elevate blood glucose levels. That's why it's superior to a high carbohydrate diet.

You can disagree with me on this, but one thing you cannot deny is that fat and cholesterol are needed to produce testosterone.  The ketogenic diet explicitly states -- high fat, moderate protein, low carb.  It's a perfect match for strength training because the high fat intake will produce testosterone, and the low carb intake will avoid massive insulin surges in the blood.