Which itself is a false concept considering the willing suspension of disbelief is willing. So no matter how little verisimilitude there is, it's still not 'destroying' anything. At least nothing of much value.
You can willingly suspend your disbelief. But that can be made impossible by the fiction.
Suspending your disbelief takes cognitive capacity - you need to get in the right frame of mind to enjoy certain Kindstod of movies, for example ornof you are very stressen or tired it can become a chore to play D&D or read a high concept SciFi or Fantasy Novel.
So in order for the Player or Audience to be able to suspend their disbelief, the weite/director/DM needs to help them by putting in as much relatable things he can.
For example:
- Characters need to react as realistically as possible to situations and not act out of character, especially in more relatable situations.
- Unless otherwise established, Humans are Humans and function like humans. That's why a lot of people got so pissed at Game.of Thrones for fat character staying fat while walking in the winter with barley any food for months.
- War logistics should make sense when they are shown. Building a fleet on a lone planet without outside support that is stronger than the whole might of the empire before its fall breaks the suspension of disbelief.
Like, the second to last example with staying fat, it didn't disturb me, it didn't break my suspension of disbelief but on an intellectual level I understand why that can be a deal breaker for others.
Because the big problem is, the breaking of the suspension of disbelief is not a conscious decision. It is your subconscious stopping to work and saying: Hold on, that doesn't make any sense!
And when that happens, you suddenly stop to enjoy the movie or game at that moment. If it is just something small, people can go back in the right set of mind, but if its something big or a lot of small things, people can enjoy the game or movie or novel anymore.
And this breaking of the suspension of disbelief, everybody had a different breaking point, but you can average it out and you can train people to do it better - which for example the Marvel.Cienematic Universe did (and the DC Universe failed to do):
The MCU starts with Iron Man, it is very ground in reality (the more fantastical hulk movie before flopped more or less).
And with every MCU Movie the slowly increased the fantastical elements. We go from a guy in high tech sci-fi suit to time travel shenanigans and parallel universes and multiverse theory.
If the MCU would have started with Avengers Endgame or the Loki TV Show, it would have flopped because the audience wasn't ready for that.
That's why new D&D players usually don't start with planescape or spelljammer but with forgotten realms. Because it is more real. And only after they get accustomed to the default 5e Setting, they can go to more stranger settings.
But not everybody can do that. That's why Forgotton Realms will always be more popular than spelljammer or planescape.