> For example: when a candidate mentions "references" on his resume, they are always meant to give positive feedback about them which is why again its broken.
Many jobs don't give any feedback at all. The purpose is to prove that you did, in fact, work there with that title for that duration.
General question: are un-vetted reviews about someone by completely unknown people a reliable indicator of future performance?
If places don't give reliably truthful reviews, why would you expect that the 360 feedback wouldn't turn into exactly the same thing?
We have a day-to-day manager (a person on the project team managing your sprint goals, day to day decisions, etc) and a "line" manager - a manager who is more HR and keeps an eye on your performance, project staffing, professional development, goals, etc. You get feedback from both, but the line manager is the person who handles the formal performance review process, reviews peer feedback, handles the promotion process, etc. This is the person you meet with at least once a month to talk about your general progress, how you're feeling in the role, how effective you are, tensions in relationships with others on the team, etc.
You can pick who you ask for your feedback (so you are free to pick people you get along with, although I tend to pick people from different disciplines who I think could provide useful information). The line manager then also speaks to your day to day manager and other people they feel are relevant but whom you may not have picked. All of this, I feel, builds a fairly good picture of your performance coupled with the line manager's knowledge of the project, company, team members involved. The line manager then interprets all of this to the best of their ability and communicates it to you.
In other words you have some level of certainty that the in-house manager doing your performance review will most of the time have a good idea of the environment and the context in which reviews are given. You can usually trust their interpretation of the feedback and overall situation (or have a discussion about why you might disagree with a certain point).
An outside hiring manager presented with a pile of historical feedback probably won't be able to interpret it very effectively - they won't know what was happening in the project, who the other people are or what their biases may be, etc. This can easily result in a totally inaccurate impression of the candidate.
Plus who would sign up to enable others to have anonymous feedback about them? If you are really good you would get hired without it, so it would be a sign that, at most, the person is a solid B-player and likely a C player. Would you hire such a person?