You must have lived in a different german reality then.
For us it was always easy to get someone else to buy your booze, if it was not already given to you somehow by the older guys. Or if you looked slightly older(I was NEVER asked for ID while buying drinks). Many people in my age group developed a drinking habit - and big surprise, quite some of them turned into alcoholics later. Also no surprise, with so many adult role models being drinkers as well.
The general principle of gradually allowing more, might help a tiny little bit preventing early access for some people, but it absolutely did not help prevent alcohol abuse. There is just a general culture of alcohol abuse (Oktoberfest and co). So yeah, we had also fun, but I strongly reject the idea, that alcohol could help preventing smartphone addicts or is somehow better. Rather the contrary as teens still drink today and can just get addicted to both.