I’m not limiting myself to combat encounters in my hypothetical. What I’m talking about is when the group wants one experience, and the game is giving them a different one (prompting the GM to fudge). For example, if a group decides to play Moldvay Basic, but they’re not interested in its take on dungeon delving and would rather explore their characters’ arcs, then that might not be the best system for them. It’s going to fight them on several levels (from encounter difficulty to how progression works).A lot of times it's an indication of poor system mastery by the GM, in that they don't know the system well enough to know how to prepare appropriate challenges for players in that system, with the result that they find they have to fudge to make the encounter more or less challenging.
I suppose what you suggest is one way to go about fixing things, but it doesn’t seem like a very good one to me. I really dislike the idea of needing to “git gud” to run a game. That should never need be the case. I would rather my group recognize when the game isn’t working and make conscious changes. For example, if we care more about dramatic moments than combat challenges, decide up front that certain enemies will have flexible amounts of hp. Such a change may have started as fudging, but it ceases to be once it goes from reactive to intentional.