Why do some reviewers say neck massagers feel painful?

Verified-purchase reviews across multiple products in this category mention that the hard plastic or silicone nodes can dig in uncomfortably, especially on bony or already-inflamed areas. A Walmart review of the Snailax explicitly calls the prongs 'extremely painful.' The fix is usually to start on the lowest intensity, use a layer of clothing between the device and skin, and reposition often.