It's just never felt to me like the resulting 30 to 50-foot putt is that much more difficult than any other difficult put of similar length. Sure, I have three putted, but I've haven't (yet!) four-wiggled. I've never walked away feeling like it was at all an unfair or impossible 2-putt, that's for sure. It was, to me, just a cool challenge to overcome.
Well, for starters, the resulting putt can be
30-80 feet, not just 30-50 feet...
Depending on your angle, the upslope will cause a significant break far earlier than a normal long lag putt. If the pin is left and your ball is in the swale on the right, or visa versa, that is a putt that golfers rarely attempt. If you misread the effect of the upslope, you can have a 6 footer or more even if you had perfect pace. Getting the pace right is really difficult. You can see the upslope and know you have to hit it firm, but once you are in the swale you tend to forget about the additional contours past the swale. First time players almost always leave it 10-15 feet short.
Give me a player at random (handicap unknown) and I'll bet three putt every time!