I haven't read the whole thread but I wonder -
Would (some of) these pupils even have got to university in the past? Likely they may have been bullied or shut down by teachers/parents at a much earlier stage and not achieved the required grades. Or played truant or dissociated at the back of a class or shunted to a special school or behavioural unit, prison, or even become more ill and potentially harmed themselves/become institutionalised/been taken advantage of by an older pupil, ending up in trouble with the law, addicted to drugs, or pregnant.
What we may be seeing is the positive results of more support and inclusion, allowing people who may have previously been too shy or anxious or socially awkward to access HE. Now that that is happening, it's important that they have the correct supports in place to allow them to access education. Access is more than just admittance.
Not to mention that HE is expected in a lot more careers these days - so some pupils may not even particularly want to be at university but feel it is their only option.
Also, these are very vulnerable young people. We know from statistics that the most vulnerable children are many, many times more likely to die before reaching adulthood from medical causes such as SIDS, disease, infection, childhood cancer etc as well as accidental or external causes such as accidents or injury e.g. by parents or self-injury.
Our society rightly considers this very tragic and so we have made lots of changes, from improved safety standards and risk warnings, to vaccines and other improvements in medicine, to changing socio-cultural norms around things like supervision and parental smoking and seatbelt/car seat use and so on. So we have successfully reduced infant, child and youth mortality and the statistics reflect this:
In 2022, roughly 5 children out of every 1000 born died before their 16th birthday.
In 2000 it was roughly 10.
In 1980, 17.
There are about 750,000 births per year in the UK (fairly stable since the mid 1970s).
So in 1980, ~750,000 of whom ~127,500 would never make it to uni as they would have died before turning 16.
In 2000, an extra 52,500 babies born surviving to age 16+
Today, an extra 37,500 babies born since 2000, or 90,000 since 1980 survive to age 16+ (yearly) - and many of these will be the most vulnerable children in our society. They may well suffer more MH problems, anxiety, struggle to manage basic situations etc.
As well as not ostracising young people who do not fit the mould, there are probably also more of them.
Later parenthood is also thought to be behind around 10% of the rise in neurodivergent conditions. And though we are better at keeping premature babies alive, we are not good at preventing the developmental risks of premature birth, so there will be more young people around with complications resulting from this who would not have survived generations ago.
I don't think it's a parenting failure - modern parenting in general is better than it has been in the past. It's only if you subscribe to hopelessly outdated ideas about "respect" and "authority", or you are focusing narrowly on a particular group of parents, that you could possibly think parenting has gone down the toilet across the board. There have always been unengaged parents and overprotective parents, and I don't think there is any evidence that rates of either have dramatically changed.
Environmental factors like social media/societal division, austerity and lockdowns could be exacerbating things. It's probably just hard to tell how much this is the case unless you look back in hindsight at long term data, and compare between different countries (most Western countries are seeing similar issues).