https://www.vox.com/policy-and-politics ... ary-rigged
An interesting take if anyone is interested still.
The primary wasn't rigged but many democratic figures and elites tried to dominate the "invisible primary" by getting hillary endorsements money and staff early before voting to scare off challengers and clearing the field.
Bernie Sanders was arguably helped by the clearing of the field.
The real takeaway is that Elites did this far too early and what was true when they started the process wasn't by the time the election happened (i.e. hillary being popular) and the lack of trust in the party and schism is a direct result of that.
An additional note is that we are currently lamenting the GOP's inability to control it's own primaries with the crazies like roy moore who thinks gays are worse than child abuse or trumps complete lack of any competence. Some role for gatekeepers exists even if only to weed out the very crazy or very incompetent candidates or those who could loose elections in places they have no business struggling in (like alabama).