The active compounds are boswellic acids. They do not survive steam distillation — which means they are not in the essential oil nearly every brand uses.
Frankincense has been in skincare for as long as there has been skincare. That is not the interesting part.
The interesting part is that almost none of it contains the compounds the research is about.
Boswellic acids are heavy, non-volatile molecules. Steam distillation carries the light aromatic fraction over and leaves the boswellic acids behind in the still. The oil smells like frankincense. It performs like a fragrance, because that is what it is.
Getting the boswellic acids out requires extraction, not distillation. It is slower, it is more expensive, and it is why we do it two different ways.