The study you posted debunks this theory. Based on your assumption less systemic DHT reduction should equal less efficacy. But that contradicts what was observed in the study.
There’s over a 20% difference in systemic reduction between topical and oral. So, if what you’re saying is true, there should be a 20% higher efficacy rate with oral finasteride. Because more DHT reduction = higher efficacy. But that is not what the study says.
Topical and oral finasteride is numerically similar in terms of hair growth (efficacy), despite there being a 20+% difference in DHT reduction.
Even the own study had this conclusion
None of your points have any solid foundation.
To summarize your points:
Oral finasteride and topical have similar side effects profile. Statistically similar but there’s still over a 1% difference in sexual side effects. Stats mean nothing to individuals. 1% of 100,000 is 1,000 so the more users the higher the number. What may seem insignificant isn’t when you look at it deeper.
Oral finasteride is cheaper and you can microdose. There are no studies comparing microdosing finasteride and taking 1mg daily. So this point is inconclusive. But worth exploring.
Topical companies rip you off by selling subscriptions. This point doesn’t have anything to do with effectiveness or safety. But even from a monetary standpoint. Topical finasteride is sold by several companies that are not expensive and don’t do subscriptions, and you can DIY your own topical. Making the cost only marginally more expensive than the oral version. Moot point.
The more DHT the higher the efficacy. On paper this makes sense but this study contradicts this theory. It’s possible that applying the drug topically reaches DHT at the hair follicle level making it similar in efficacy as consuming it orally. There are no studies proving this but this speculation makes more sense to me based on this study.