Let's do some maths.
Say you get a starter job paying 20k a year, i.e. 17.5k after deductions, or 1.5k net each month.
Assuming your parents are happy to let you live at home rent free for four years and that you spend very little in that time, you might just save 1000/month, i.e. 48k in four years. This would allow you to buy new clothes from time to time, have a basic phone contract, pay for travel costs, the odd night out or dinner with friends etc. but you probably won't be able to afford a holiday or a car. If you're lucky, your parents might pay for driving lessons and put you on their insurance.
Let's be optimistic and say that at the end of those four years you have been promoted, earning 25k a year and have saved 50k at the age of 22.
You find a bank willing to lend you 4.5x your salary, which is around 120k, giving you a total budget of 170k to get on the property ladder.
So yeah OK, that would get you a starter home in cheaper parts of the country. If you happen to be from a more expensive part of the country you have no realistic prospect of buying anything unless you leave your family, friends and entire support network and move somewhere cheaper.
But that's really your best case scenario, assuming four years of being supported by parents without having to pay rent or bills and living extremely frugally. And then what? You don't have a degree, so unless you work for a company or in an area with really good training and development opportunities, your earning potential is probably going to level off quite early. Meanwhile, you have a fairly high amount of mortgage debt relative to your salary, you're very vulnerable to interest rate rises and you're not getting the kind of pay increases which would normally reduce your risk exposure over time.
None of the above factors in other things you might want to save for either, such as pension contributions or a rainy day/emergency fund.
If you have or find a partner in a similar position to you - which is unlikely at such a young age - and you decide to pool your resources, then yes, you probably could buy a fairly decent home. But that's a big if. In the best of circumstances, money is always going to be a bit tight. If your partner has less money than you then things will be even tighter and you would be better off not marrying, at least in the short term.
Then at the age of 25 you decide to start TTC with the aim of having completed your family by the time they turn 30. What happens after maternity leave? You won't get any help with childcare until your child turns three. If you are from a cheap part of the country and have managed to stay living round the corner from your generous and helpful parents who so kindly let you live at home rent free for four years and they happen to not be working themselves and are happy to provide free childcare, great! Otherwise, you will most likely find that your wage is completely eaten up by childcare costs, leaving your partner to finance those mortgage repayments and all other bills on their own. And that's before you even think about having a second child.
As far as I can tell, that's just about the best case scenario for the kind of person you are describing.
I could have done that. At the age of 18 I was working in a full time job earning 18k a year and living rent free with my parents. I intended to go to uni the following year but I didn't have to. I could have stayed where I was. The company had great training opportunities and decent career progression, even for non graduates. Some of the people I worked with who stayed there have done pretty well for themselves, despite being in an expensive part of the country.
But I didn't do that.
I went to uni, studied one of the useless subjects about which the OP and various others in this thread have been so scathing, with only 6 contact hours per week. I spent too much money on nights out. I spent too much time mucking around and having fun. I graduated with a student debt - admittedly a much smaller one than today's graduates are lumbered with - and a degree in a non-vocational subject with no clear career path. I did a few internships and got a graduate job offer which required two years of additional study before I could start. I spent those two years studying, doing part-time work at weekends and holidays, and travelling when I could. I decided I liked the travelling and put off the graduate job for a further year so I could do a lot more of it. I finally started my career at the age of 25, at the bottom of my overdraft, crashing with a friend for the first couple of months, and without having paid off any of my student loan yet. I didn't even have a boyfriend, much less a husband, and it would be another 8 years before I managed to get on the property ladder. I did make an effort to save money consistently, but I also spent a lot on rent, travel, and another degree which I did part-time whilst working.
And now, in my mid 30s, I am married to the kind of man I never would have had the opportunity to meet if I hadn't done these things, living in a foreign country, I have a child and another one on the way, with a salary that is several times what it would have been if I had stayed on that first career path, and a much more expensive home than I would have otherwise been able to afford.
I made a lot of the choices and did a lot of the things which are being looked down on in this thread, by the OP, you and various other posters, who presumably would have advised me to stay in that first career path and just keep toiling away in an OK job for an OK salary. And yet I am far better off - and had a lot more fun along the way - for having made those choices than I would have been if I'd followed your advice.