I actually agree with a lot of that. The problem with addiction - well life in general really but addiction especially - is that you can't help somebody who doesn't want to help themself. Are we really going to continue to throw thousands of pounds at somebody who has zero interest in trying to get clean/improve their life? How many times do you house them and them **** it up before enough is enough, 5? 10?
Your point about addiction leading to a lot of this is a fair one but while it's a contributory factor it doesn't excuse poor behaviour and you're still responsible for your actions. Which is why saying "I was drunk" in court won't prevent you being convicted of an offence.
Look at my situation; kicked out at 16 and straight into a hostel. Kicked out of that 5 months later for breaching visitor rules and having drug paraphernalia on the property. 6 months homeless and then into another hostel just after my 17th birthday. There for 8 months and then kicked out for alcohol/drug induced noise complaints (people didn't like hearing happy hardcore at 4am on a Tuesday

).
Are you seriously suggesting that after all of that I wasn't at fault for the situation I found myself in? Yeah you could argue that placing a 16 year old in a hostel with ex addicts and alcoholics increases the chances of my downfall accelerating, but ultimately I behaved poorly and with that came consequences.
As an aside, the drug support networks are largely archaic in this country with us being miles behind other nations. But that's a separate if not completely unrelated debate.