Haven't used VSTHost but that is a kind of default folder on Windows where most VST's will install. Typically you can set a default folder in a Host which the host will then scan for available VST's.

MainStage 3 | Axiom 61 2nd Gen | Pianoteq | B5 | XK3c | EV ZLX 12P
Hoping everyone stays safe and well and sees this through to the other side