Catching drug kingpins is about publicity for the police and the unaccountable revenue stream of seizure proceeds for bonus income and toys for cops.
It is well known that the ostensive purpose of prohibition -- the reduction of harm from drug addiction -- is not served by going after kingpins and cartels. There are always candidates to replace kingpins waiting in the wings and catching them only promotes violence as the candidates vie for status.
The effective policing tactic is to arrest middle class casual users and subject them to the shame of felony records and probation. You hunt down the soft targets at their homes and parties in vast numbers and hit them where they care -- in their job prospects, reputation, and freedom -- by briefly imprisoning them long enough to disrupt their jobs or school. Then you require them to report for weekly drug tests for years with a guarantee of longer imprisonment if they use unauthorized drugs again.
But the middle class voters won't support the drug war if you do that and there's no cash reward for cops in it or big media display either. So we're stuck with the wasted effort and public violence of going after kingpins.
And the credulous public always goes for the lie that the really important work is going after kingpins. Somehow it sounds meaningful to people who haven't thought about the subject. It's the opposite of effective policing, though.
See, I don't know ... DPR was definitely a big fish, but only in a certain context. He obviously had the technical chops (and moral compass) to set things up the way he did, but at the end of the day, all he did was facilitate business for other (IMO) much bigger fish.
I'm not in any way justifying his actions or anything like that. But I too was surprised that they just shut it down instead of just assuming control and going after what could have turned out to be cartels (assuming it wasn't just small time growers, etc.).
More likely than not, some of the drugs sold on SR were produced by cartels. The SR sellers were probably so far down the supply chain that they could not have given the police any useful leads on the cartels.
In case people have forgotten, SR itself was a target. There was pressure from Congress to shut it down, and it was probably the only goal of this operation:
I'd imagine there were a relatively small number of well-rated suppliers servicing the majority of trade, and fewer still producers. If DPR was in fact taking a ~10% cut, those suppliers would have stood to make considerable sums of money given the profit margins involved.