Absolutely. Silk Road was a mostly (not completely) illicit marketplace and the characteristics of illicit markets is that money transfer has tons of friction. You can't use regular bank accounts, cash works but sending cash around the country or the world is problematic, risky, expensive, slow.

So bitcoin was a perfect solution to that problem. It naturally gravitated towards a market with very little competition and shitty alternatives. Of course it thrived.

Bitcoin could never have taken off if it had tried to become a currency in stores first. It needed a proof-of-concept. And the only market it could do that in, was a market with no competition.

So bitcoin blew up there, and now it's slowly making the transition into the mainstream where it faces much more elegant, entrenched, competitive players like debit/credit/ach/cash etc. Despite these being far from perfect, it's a big battle. But without Silk Road, bitcoin would never have had the momentum, the interest, userbase, hype or infrastructure to even think about competing for mainstream use.