What Ulbricht provide is a market for trading so called illegal drugs and other goods. If those goods are traded in a face to fact manner, then there will be more gun battle between drug traders and will waste a lot of police time.
Anything that facilitates drug sales feeds the violence further up the food chain. If SR had been linking drug makers directly to consumers with none of filth in between then it would be a noble endeavour. I'm sure it did in certain cases but it was still responsible for plenty of misery.