It wasn't super secret, it's just that the HTTP protocol standard is getting quite large. HTTP standard site.
Same with HTML, the standard for HTML 5 is just so massive no one person can know all of it. It is completely unknowable to a single person at this point (without referring back to the standard).
The protocols and standards underpinning the Web have become over engineered in my opinion. I'm sure it was with "best intention" but I recommend gemini protocol at this point for "fun" and http for "business". Corporations owns HTTP at this point and there's little that can be done to change it. It has become the modern Adobe flash with the veneer of openness to satiate the causal observer.