That was my thought exactly when I first heard about this. Why on earth didn't the capitol police, AR15s at the ready, warn the mob as they gathered against the barricades that anyone who breached them would be shot dead? And then followed through on the first person or persons who did?

Would the mob have pushed forward across the dead bodies, hoping to overwhelm the police?

I strongly doubt it. My sense from what I've seen is that they are/were a cowardly bunch, full of self-aggrandizing bluster, but empty of a willingness to put their lives on the line to follow through.

So really, the blame for the capitol riot lies with the capitol police. I believe I saw a report that their chief committed suicide. Apparently he agreed.