To elaborate- For paint/primer to adhere well some surface roughness is needed (for the coating to bite to). Highly polished anything (like chrome or stainless) is a poor surface for this bite.

While I'm sure some sort of "anti chrome (and nickel's layer as well as the base layer of copper) depositing" coating/masking is possible the usual is to try to limit the polishing to what will be exposed and dip the frame only as far as needed (in the manufacture's, the plater's opinion). It's not uncommon when stripping off paint from a bike that has chrome lugs or stay ends to find that there's chrome for quite a few inches past the exposed locations.

A well known example of this is the early 1970s Fuji Newisets and Finests. They were fully chromed but only the lugs, tube center panels, blade and stay ends were polished. It was quits a discovery to find the BB was still really rough but chromed under the paint I stripped from my 1972 Finest. The rest of the tubes (not including the polished panels) were also chromed but a smooth yet dull surface. Raleighs of the same era that had chromed stay/blade ends usually had the chrome peter out a few inched above the paint edge.

Chroming requires a dip into some pretty corrosive chemicals to clean and etch the surface just before the copper is applied. If these chemicals (usually acids IIRC) are not well flushed out of the frame's interior they will eat away the frame from the inside. Additionally Hydrogen gets absorbed into the steel during the electroplating process and if not baked out after plating hydrogen embrittlement can develop, further weakening the frame. These and other work condition and environmental issues have led some states to regulate the chroming process, to a degree that many platers have changed their processes of offerings all together. Andy