Rejecting someone's idea or proposal can be extremely challenging because
a. few form letters on which to model your letter exist.
b. you may also have to fire the employee for coming up with the idea or proposal.
c. the person probably has invested a considerable amount of time developing the idea.
d. you do not want the reader submitting any more ideas or proposals.
e. most employees have low self-esteem, which you want to delicately maintain.
Answer: the person probably has invested a considerable amount of time developing the idea.