Agree (in principle) with Jack.

A few decades back it was common practice to remove the board outline from all layers but the layer containing the dimensioned fabrication / drill drawing. We also included "alignment targets" on all other gerber layers so they could be aligned at CAM ... always seemed wierd to me removing 1 alignment feature (outline) and substituting another.

I also found I was consistantly getting requests for inclusion of artwork layers with board outlines for alignment of layers without from various groups (CMs, Stencil Vendors, etc.), and hence now include the board outline in all artwork layers.

Here's something to ponder ... if your fabricator has a CAM department who has difficulty removing a simple unwanted board outline during tooling do you really want them building your design?