Just finished answering the survey. Honestly, I am not a security expert though I do know the basics here and there which is why I answered to the best of my knowledge. A small portion of people would have actually successfully traced a Bitcoin TX through different methods based on my research.
I'd even say small amount of people would even try to do that. I use Bitcoin from time to time. Sometimes I browse transactions to see how they are doing or to see amounts of money in the wallets, but I've never needed to trace a transaction, I just did the browsing out of curiosity. IMO the fact that there are no named attached to wallet addresses is enough for privacy.