UK-style streaming enforces a rigidity that have lifetime implications if someone is unlucky enough to be on the wrong side of the score.
In your system, despite having technical talent, low secondary scores would have shunted me off to a vocationally-oriented school that would provide a very limited scope of highly precarious work opportunities. I would have to possess some favorable peerage status (or be from a very wealthy/influential family) to overcome that in any reasonable amount of time.
On the other hand, the US system allowed me to fix my issues, attend a good university, and graduate at the top of my class. That, and I managed to find good FTE work for a non-agency-based employer during said education - something equally impossible for my UK equivalent.