S76 Heavy VRS is usually caused by "pilot error" too (and is 100% preventable too). As you say the label of pilot error is usually attached to any hard landing due to insufficient power. As we all know, an error may not have been made at all.
For instance; you are on short final, and have done every single kind of recon known to humans, you note where the prevailing wind is, and the surface wind, and then the wind can still change suddenly and become a downdraft causing a hard landing. I would be rather cautious to call that kind of scenario "pilot error". You only have to ask anyone who heli-skis, or just flies at something higher than sea-level, and a hard landing can be just a gust away.
Cheers
Randy_G
