By the time I went to university in 1978, I'd done quite a lot of caving, and I knew I loved it. I lived in London, but I'd been down many caves in the south of England and Wales as well as a few in Yorkshire. Some of those systems are now effectively closed to under-18s, including St Cuthberts, Longwood Swallet and Agen Allwedd.
Naturally enough, when I started uni I joined Oxford University Cave Club, which was then an incredibly strong, keen group, organising numerous, well-attended meets every term and in the vacations, culminating in the expeditions to the Picos that saw us explore Pozu del Xitu down to its first sump at - 1135 metres. Quite a few of us had been active before getting to uni, and that meant we had skills and experience to pass on to others to help create our team.
Nowadays, access restrictions, at least in Wales and the South, make it much more difficult for teenagers, and the knock-on effects are clear. Several once-proud university clubs have folded. Others - sadly, Oxford included - are a great deal smaller and weaker than once they were. OUCC mounted expeditions to the Picos every year from 1979 to 2012. It's no longer strong enough, which is why the exciting onging explorations in "our" former area are now being carried on by the Ario Caves Project, which is only loosely linked with Oxford, and run by Steph Dwyer and Mike Bottomley, who have never been OUCC members. (And who deserve much gratitude for keeping the flame burning.)
That's just one argument that illustrates why the whole sport is weakened by unnecessary and illogical age restrictions. To keep up their interest, once they are past the beginner stage, young cavers need a steady supply of challenging, exciting trips, that preferably don't require them to spend many hours in a car. I remember when the Lancaster University club fresher weekends needed coaches to transport the new recruits, there were so many of them. You'd see them parked in Ingleton. On the back of that influx came many discoveries in England, and the exploration of magnificent caves such as Cueva del Agua and 56 ( - 1169 metres) in Spain. LUSS no longer exists.
Age restrictions are part of the reason for this saddening decline.