Why not use "Both" in a gRPC proto project?

Question

I want to use the "Both" keyword instead of "Server" in a separate project for .proto files in a solution with both a server and a client project. But the company's software architect and teamlead say to avoid using this. Why so?

  <ItemGroup>
      <Protobuf Include="**\*.proto" GrpcServices="Server">
          <ProtoRoot>Proto\</ProtoRoot>
      </Protobuf>
  </ItemGroup>

What were my efforts to solve the issue is that I tried to tell them is it more convenient and no need to create separate .proto copies.