For the same reason tobacco ads are illegal, yet you can still buy cigarettes. Prohibition doesnt work, thats why we have rules and regulations. Advertising something that is highly addictive should be highly regulated.

Here in the USA it's how they get the poor to pay back the natives, instead of taxing the wealthy heirs of stolen land.

One step at a time.

Because it shouldnt be popular, but making it completely illegal is quite invasive.