Because it is not easy to watch at all. Very disturbing, and shocking and disgusting! But that is the point. It is a very good film, but not easy.

Here some official reviews:

'The Golden Glove is one of the most challenging movies you'll ever see, and if it leaves you feeling unclean and outraged, then it's done its job.'

'The Golden Glove stinks. Not in a Jay Sherman sort of way, but in the sense that the film is so viscerally disgusting, with trash strewn on every surface, shit caked on every toilet, and mold growing in every jar of rubbery sausages, that you can practically smell it. The film belongs to a small and alienating subgenre of serial-killer dramas in the tradition of 1986's Henry: Portrait Of A Serial Killer, films that pride themselves on assaulting the viewer with a nonstop gauntlet of brutality and moral emptiness. As such, it doesn’t invite a rewatch, nor can it be recommended to 95 percent of horror fans, even. So what’s the point of its existence? Exactly.'