Good, I can't imagine why it was ever 16 (except to deal with otherwise illegitimate children, as many 16 year olds have always been sexually active).
I really don't think your average British 16 year old is going to be rushing off to Gretna, OP 😂 And anything that makes arranged marriages of children more difficult is a good thing. I was most definitely not mature enough to be living on my own at 16, though I suppose I would have coped(ish) if I'd had to. I'm sorry you were in that situation.