Whenever someone complains about characters’ inconsistent power levels throwing them out of a story, or talks about how powerful a character is supposed to be in any context, someone shows up to go “only nerds care about power levels, real writers just change them at will for the sake of the story”.
This is bullshit.
Power levels are stakes, and stakes are power levels.
It matters whether the person the heroes are fighting is a serious threat that can kill them, or a joke they can easily clown on. It matters if a single hit will kill or maim the hero and must be desperately avoided, or will casually bounce off their chest.
A very common mistake in superhero media, especially, is fights that don’t feel like they have any stakes or matter in any way because they’re just sort of fighting without any impact, until the writer arbitrarily decides one of them wins; and they’re all just sort of vaguely interchangeable because the audience – and, one suspects, the author – has no idea how strong anyone or thing is supposed to be (or, in the worst cases, what their powers even are.)
A gun, deliberately shown to the audience, creates the implicit stakes that someone might be shot – because humans that are shot with bullets are seriously injured or killed. If a character is holding the gun, let alone pointing it and someone, that increases the tension further. But only if the gun is a threat. Superman being held at gunpoint is not tense because there is no threat.
Let’s take The Boys as a case study. When Homelander casually puts his hand on someone’s shoulder, you feel the tension and implicit threat instantly, because it’s been so clearly communicated how easily he could kill them. Conversely, if Starlight puts her hand on someone’s shoulder, what does it mean? She’s … vaguely stronger than a normal woman of her build, probably even superhuman, but it’s not clear what she could actually do to someone if she tried; let alone where she stands physically relative to most of the other superhuman characters.
In some cases, power levels may matter more because they’re key to the themes of the story/character. Superman doesn’t work if he’s not super. John Wick doesn’t work if he’s not the bogeyman. Galactus doesn’t work if he can’t devour worlds and make heroes look like insects. Lovecraftian gods don’t work if they don’t inspire cosmic horror.
Conversely, obviously, stories that aren’t speculative fiction and/or focused on combat may not need to deal with physical power levels as explicitly. But that doesn’t mean they aren’t present. If a physical threat – a gun, a fire, a heavy weight – comes up, we can generally tell the relative “power levels” from our knowledge of real life, from context, and from a character’s appearance. Even so, if your action movie has the hero casually avoiding gunfire by rolling out of the way, you have established that these enemies have crappy aim and they will feel like a joke – if you want them to seem deeply threatening later, you will need to give them some kind of “power up” or the stakes won’t be there (and if they materialise regardless, it will seem dissonant.) Even if a story has no physical threats whatsoever, the social and intellectual power of the characters still matters deeply for establishing the stakes and tension of a given scene or narrative.
So what is true?
First of all, it’s true that an audience will generally forgive or miss a certain amount of inconsistency and lack of realism if they’re having fun with the other aspects of the story. This isn’t limited to power levels, people are just more inclined to nitpick if they’re not having fun, and willing to handwave things and suspend their disbelief if they are. Especially in longer works or shared universes, where we know consistency can be hard – if they’re having fun, people may be willing to give the writer a pass for even quite blatant contradictions. This does not allow you to get out of clearly establishing the stakes (i.e. power levels) within a given scene or story.
Secondly, relative power levels matter more than absolute ones. Absolute power levels do matter, because they’re just power levels relative to specific real-world things. But if, say, a character’s role is to be more powerful (in a specific field) than anyone else in the story, then the upper limits of their power can often be left vague. A lot of superhero stuff kind of gets away with vague power levels by having most of their characters be vaguely above “mundane” threats and vaguely able to hurt and withstand to each other, although this lazy approach easily runs into issues, as I’ve talked about. This gets into the whole “Sanderson’s laws of magic” thing where you only really need to establish rules that will come up, or at least you want the audience to think might come up.