There is one big advantage when using a projector - You can place the center channel speaker behind the screen. That allows a good quality loudspeaker to be used.

Most center channel speakers that are designed to mount below a television are terrible. You really can't make a good loudspeaker that's short and wide. The typical design uses horizontally arrayed drivers, which then create lobes and nulls in the listening area. I'd rather have a phantom center than that.