Scrum is widely used and also widely disliked. I find that apologists for scrum generally excuse the dislike as 'that's not how scrum is supposed to be implemented' - just as you have here. It's exactly the same form of argument you get from apologists for Marxism or Communism when confronted with the widespread dislike for those systems. If something has generally failed wherever it has been implemented, it's not because it hasn't been implemented properly, it's because it is fundamentally broken.