But there are also multiple mountains that get crushed here? Like, why would he not crush multiple mountains in multiple steps? I could easily see this being about a dragon that rampaged around and left a big area devastated.
and? You don't crush grapes bit by bit, you take whatever tool you use, you apply pressure once and boom, their juice is out. Why are you saying that the assumption that the uncommon narrative of crushing a mountain in one hit is worse than the assumption that it's crushed in multiple hits? It specifically states crushing, him rampaging would imply he'd also hit them around. Meanwhile the word "crush" was used here, not "destroy".
You... are making assumptions on why the dragon was crushing those mountains, which we don't know. Nobody said it's random mountains. We don't know the dragons motivations or which means it decided to crush them by. Fundamentally, I don't see the difference to "can destroy x" statements, where we also don't assume that it definitely was done in one attack.
Crushing can only be done via applying pressure, aka, not hitting them, not splitting them, not vaporizing or pulverizing ect. Narratively, someone crushing something with a single attack is far more likely than a specific implication that you did it in multiple attacks.
The difference between other feats that are over time and this one is simple: often in fiction when someone destroys the world or destroys the universe it is shown that they are doing that overtime or in a specific manner, like The Rumbling from AoT being done overtime with 8-A characters or something slowly devouring the universe bit by bit until it's gone. These things happen often and often due to authors not thinking on planet-busting or universe-busting scales.
But here's the kicker.
When someone is stated that he is going to destroy the world/universe the main factor is often the fact that this will kill everyone in the world/universe. Meanwhile, in this case, it is a matter of showing a feat of strength. It is specifically the fact that the chains are so powerful that they can restrict a dragon that can crush mountains, directly explaining that the chains >>> the dragon so that Erma one-shotting them becomes that much bigger of a feat.
Now explain to me, why in the world would an author, who clearly wants to show that someone is very powerful and uses the statement that they can crush mountains to show for it, would say that he can crush mountains only to imply "oh but he didn't crush mountains in one attack, he specifically did multiple attacks to crush them"? Like how does this make sense? How? This isn't some passing statement that can be interpreted in many ways like "humanity destroyed several mountains to build their cities", this is a statement that directly implies that this is a feat of strength.
