The problem being, of course, that it appears that many people who were criminally involved will in fact not be charged. It's not 'prejudging' to demand that people who have confessed to crimes already be charged with said crimes, particularly in a rape case. After all, very few rape cases make it to court and almost no rape charges are lies. It's unacceptable for a prosecutor to undercharge in a rape case, particularly where there is a stack of evidence, particularly where the community appears to be on the rapists' side, particularly such an aggravated and horrific crime. Every effort should be made to encourage other women to come forwards. While not abandoning the presumption of innocence*, it should be made very clear to a rape victim that they're being believed, that the prosecutor has their back and that therefore everything that can be done to bring the perpetrators to justice will be done.
In the absence of responsible behaviour on the part of the prosecutor, people are taking the law into their own hands. They're not saying that they should face punishment without the right to a trial, we're saying that they're probably guilty, will never face a trial and mild extra-judicial punishment is better than scott-free. Now, we might not agree, but the fault is entirely the prosecutors. Where law fails, vigilantism takes over.
* I think this is a grey area. In my view, some standard rules should be modified in rape cases, because they are so emotionally damaging, ect (which is, of course, what is happening). Theoretically, the defendant has a right to face the accused; probably not in a rape case. Cross-examination is often used in a manner just skirting the edges of probity (dress, previous sex life) in order to label the defendant a slut; this should be prohibited immediately, though I admit it is thorny. Not to mention the inhuman process of making a rape victim relive their attack. I understand that courts have been grappling with this for a while now and good for them (so no names, video testimony and so on) but I think more could be done. The danger of accidentally imprisoning innocent people is serious, of course.
TLDR: Basically, I'm saying be nice to rape victims; it's complicated, sure, but prosecutors should support their brave decision to go public.