The fact that some DC will never be able to get a 'good' GCSE does not mean one should abandon thousands other perfectly capable children on the scrap heap, failed by the system.
Surely those that really cannot get GCSEs are tiny minority with specific reasons and circumstances, such as SEN and cognitive assessments reports that state their supposed IQ and that they will not achieve mainstream qualifications. The estimate is that only 2.5% have IQ below 70 and 5% below 80. And IQ should not be the end of all, "we are talking about just a few points", as Forest Gamp's mother would say, and professionals would/should be reluctant to say in most circumstances that such and such will never achieve GCSE.
The EHCP extended to 25 years supposedly for a reason, children should be taught GCSEs, not just 'resit', but be re- taught.
Ideally all children should be taught right the first time. If teachers were accountable to get good GCSEs for all mainstream students, they would teach to this result. Now they have licence to live many behind without good reason.
All children should be on the flightpath to at least a 4. Sky is the limit, but there should be a floor of 4. Lower sets should be taught in a way to plug the gaps and accelerate learning, to get at least a 4 at GCSE.
It is not right that children with ability in "average" range, including those with SEN, pushed into mainstream education are denied the qualifications which are a gate to progress in life. Teachers should be accountable to bring them to success.
One cannot seriously argue to go back to the 60s or whatsit time when GCSE were not needed. This is absurd in 21 century, with all the technology and fast changes. People need certain level of general knowledge, awareness, certain level of judgement, decision making, level of preparedness to adapt and learn further throughout their lives.
Surely education system that leaves behind 40% without looking back is a legacy of the outdated expectations of 'class'.