My personal experience is that your statement is FALSE.
A few years back I severely twisted my knee. Physical therapy got it moving, but there was still pain and noise. I saw collagen at Costco, somehow remembering it’s good for joints, and knowing I could return it. My research showed there are multiple types of collagen with type I only in many supplements, but the Costco product had type II which is good for cartilage and joints. It worked. I’ve continued to use it this day.
My wife started and has improved skin. It should be noted we don’t eat many meat products and take 2 or 3 per day rather than the 6 pill daily dose. I’ve recently added bone broth which is high in collagen.
Collagen breaks down in your stomach. It never makes the blood stream or into your system. Well known science(somewhat.)