What do you think about systemic yeast infection? why is it not scientifically accepted when vaginal yeast and thrush is?

Doesn't exist: That's a little like asking why there's no "athlete's foot of the heart." there are many infections that can be external or mucosal but don't cause systemic infections because of the nature of the organism. Candidiasis is one of them. Except when it's spread through the bloodstream due to injection drug use or infected intravenous catheters, it's a fungus that affects mucosal surfaces.

Blood & bowel : Yeast provide various issues with raw skin & mucosal surfaces of the body but are a benign hitch hiker when they are in the bowel. They are about 5% of the dry weight of your poo & live happily off nutrients left after human metabolism. The only systemic yeast infection occurs if it enters the blood. You are likely deadly sick & if the yeast is not quickly killed, you soon will be.