Absolutely this. Too many projects have less than successful outcomes as a consequence of factors outside the project and people involved. Your performance on a project can be measured well because of success of project while you did relatively little, or rated poorly because of personality clashes while work performed was good and productive. If in house corporate HR controlled ratings have these sorts of problems, I don't see how and external distributed one will do better. Many people rely on glossing over or ignoring bad projects, or bigging up small roles to advance themselves, having an un-editable history of projects, outcomes and performance would be detrimental.
I see this as someone jumping on the blockchain bandwagon were there is no purpose for the blockchain. Now cross-project, inter-company payments to allow you to join different teams would be a good idea.
The rating and feedback system needs to be specific to both individual tasks and overall project success. It's a good point and highlights how closely the task needs to be met with success criteria. In any case, a transparent system where both voices are clear that also has an open mediation platform has the potential to be fairer for both sides.