The topic is about fudging dice, not so much about encounter design. Yes, they can run parallel, but no DM can account for a run of dice like they saw and still keep the game challenging most other times.
Really? "No DM" can plan for bad rolls?
Fudging and encounter design don't simply run parallel to one another; the former is often a consequence of the latter. Look at all the examples of fudging presented here: adventurers overmatched by an opponent, adventurers missing a clue, players with a bad run of rolls.
The consistent argument is that fudging keeps the game fun, but what is it that's making the game fun in these examples? It's the players and their characters succeeding where they would otherwise fail. And why are the adventurers faced with failure? Encounter design appears over and over again. The adventure designer or referee didn't understand the monsters' abilities, or put in too many opponents, or made the clue that advances the adventure too hard to find. Failure is un-fun, so it must be done away with on a case-by-case basis.
Is fudging really the best way, or the only way, to solve these problems?
The other reason oft-cited for fudging is system failure. The challenge ratings are wrong, critical hits are too poweful, the exploding dice mechanic is mathematically wonky,
et cetera.
Barastrondo argues that no system is perfect and a steady hand on the wheel is a good way to steer around those design potholes.
But here's something I noticed over the years: the more complex the rules, the more moving parts, the more likely system failure will impinge itself on the game. So this is a choice as well.
My personal preferences are choosing a simple, robust system and adopting a social contract which says the results of the game are the results of the game.
As an aside, I find it ironic that some gamers complain about systems to rely on "GM fiat" or "handwaving," but in my personal experience more than a few of those same gamers want their referees to fudge "when it's appropriate."
In for a penny, in for a pound, I say.