Yep, and the appropriate response should be via the legal system, not inciting an internet witch hunt.

Appropriate? It's not for us to decide that. And the legal system is an imperfect remedy that is not available to all. Just guessing here, but perhaps the artist in question can't actually afford a legal team?

Further, if you actually read what the artist wrote, the wording is actually quite polite and gentle. It is not threatening and does not incite.

Oh? Well then by all means, let's all play pretend legal experts and decide the fate of the accused based on this single one-sided blog post. I'm sure that's never gone wrong before.

The culprit had plenty of time to resolve this issue, inciting a "witch hunt" will only spark a faster response from her.

You've just perfectly demonstrated my point. Accusation does not equal guilt, and there is no reason for any of us to believe it is on the accused to resolve anything at all.

Being a copyright issue the author is well within her rights to send a DMCA takedown and initiate legal proceedings, which is all the "spark" that is necessary for a timely and appropriate response.