Just gonna put this out there, 13/14 year olds don't have some kind of natural excess of serotonin and dopamine in their brains that constantly makes them feel awesome. They have the same reasons as anyone else for getting drunk and/or high. It's not like the alcohol affects them differently.
Now we know that consuming alcohol <21 has a negative impact on the development of brain functions that were developed during the period of (and shortly after) inebriation. This actually persists into adulthood in a less chronic form, things that are learnt while drunk are much more difficult to retain. There's also a correlation between alcohol abuse during development and mental health problems in adulthood.
That said, it's really not that much better to drink at 16 than 13 from a health perspective. The only reason we feel like it's better to drink at 16 is because we view 16 year olds as more mature and somehow better suited for handling the effects of alcohol. Maybe that's true, I would definitely feel more concerned if I saw a 13 year old stumbling around drunk and alone in public rather than a 16 year old. But I don't feel it's my place to pass judgement on someone for making a choice of their own while knowing the consequences. There's plenty of worse things that Machaty could do (and does do -- MXE has much greater mental and physical health risks than alcohol in ADULTS, let alone children) to himself than binge drink every once in a while.
