I noticed that many Request for Proposals (RFP) include a section called "Proposal Evaluation Criteria". Why is that? Because it will show the proposers how your evaluate him/her which make him focus of the hight points and get the project.
Including the evaluation criteria allows the respondents to better understand the priorities of the RFP requester so they produce an RFP that is as tightly aligned to what the requester needs as possible.
It doesn't confer any unfair advantages on a recipient of the request because all recipients receive the same information and so all Proposals will be as attuned to the evaluation criteria as possible.
Consider the (fictitious and somewhat over-simplified) situation where a recipient believes the RFP requester will make their decision primarily on a cost basis. The respondent will strive to deliver a proposal with the lowest possible absolute cost, in order to attempt to secure the business. In doing this they may choose cheaper materials, procedures or methods. If, in fact, the RFP requester will primarily make their decision on the skill and experience level of the personnel working on the deliverable then our erstwhile proposer may rule themselves out of consideration on the basis they choose to concentrate on reducing cost rather than enhancing personnel "quality", whereas they might easily have been able to provide top quality personnel if they had realised that was more important than cost.