I don't find this to be true in general. I don't shoot VV powder but tend to shoot magnum primers on any cartridge that burns 60+ grains of powder. Check out primer brisance testing. Win primers tend to be the hottest. A win LR is almost as hot as most of the magnum primers - especially Rem. I tend to use WLR for all loads, if they group well, and WLRM for all loads shooting 60+ grains of slow burning powder.

I don't know VV powders but find it hard to believe they wouldn't want a person to use a magnum primer with large doses of their slower powders. The example you listed is a good example.