"The flaw in these arguments is that if a dc can’t manage an open day on their own, how will they manage university"
I'm sorry, but I don't think that this ^^ is a valid argument. How will children ever develop self confidence if they don't naturally have it in the first place, and aren't given a bit of a boost to start with? Some 16/17 year olds just don't have that innate confidence to make the first step.
The sink or swim approach simply doesn't work with some children. Would you rather just watch them sink or give them a floating aid to start with just to build a bit of self confidence, so that they can then set off on their own without it?
I have watched my daughter's confidence grow so much over the last year. It has been gradual, but this time last year she wouldn't answer the house phone, wouldn't talk to anyone she didn't know on the phone, wanted me to come into the GP's surgery with her, was needle phobic, wouldn't travel on her own on public transport other than the school bus or our local train service.
Now she will ring the GP, ring to enquire about job vacancies, travel about the UK visiting friends at their universities, she has just come back from an interrailing holiday with her boyfriend, and has three tattoos!
She managed this because she just needed a confidence boost at the start, and I am so proud of what she has achieved.