Disagree, since I'm doing it right now 3 years after uni.
I'm not paid amazingly, below average salary for London but above average for the rest of the UK. However half my paycheck goes on rent. My commute is about 45 minutes by tube or 20 minutes by motorbike so it's not too far out. The trick is to find an area that's stabby enough to be cheap but hipster enough that there's decent bars in the area to help you forget. However I definitely got lucky, my rent is a few hundred pounds below market value.
I don't know how you manages your finances but for me anything above 25% of your income going for rent is absurd. And you are not making it up in distance, either. 45 minutes by tube is a lots of time. (I assume motorbike is not a favorable option given London weather).
I'm counting 45 minutes tube/20 minutes motorbike as close because for London that's honestly quite good. About half of the people I know have commutes over an hour each way, at least one above two hours, and I can cut my public transport commute to 35 minutes if I time everything right. Biking is actually the favourable option but not possible if I'm drinking, and the miserable weather doesn't bother me.
I would love to cut my rent down to 25% of income but it's honestly not possible without increasing travel costs and time. Plus I work in computer security, London is one ofthe few places in the UK with any job mobility in my field.
If your salary is around £30,000, you'll take home around £1,900 a month after tax and student loan payments. Spending 50% on rent is already huge, spending £300 more (66%) would be madness.
Either way there's not a huge amount of choice in London. I had to find a room in a flatshare a few years ago and I struggled to find anything under £700 which was remotely reasonable (ie double bed, room for a desk and some floor space).
Can't give location, sorry. I've doxxed too many people before on less information.
Looking at median London salaries from 2015 (which I have to hand), and assuming a 10% increase on that, you earn more than average for all but two boroughs - Tower Hamlets (i.e. docklands) and the City
[1] http://www.itv.com/news/london/2015-11-19/how-does-your-sala...
Which in other European capitals is an age where you would more likely live with your partner and start a family, rather than live like a student.