The reason why i recommend distinguishing the evidence used in an enterprise architecture artefact is threefold. The first reason is that it should be clearly marked to show to readers that evidence has been used and that they can analyse the topics, references and proofs themselves to make their own judgement to its validity and certainty.
The second is to track and trace the use of the evidence in artefacts that support the overall goal or objective of the activities.
The third is to enable a better understanding of the value of the evidence at particular points in the future. If it is determined that the evidence used has been critical in the delivery of the objective or goal then that will not only justify the time, effort and cost of building the evidence but also it justifies the need and necessity to use evidence in the future.