Destroying the earth is very possible but why it never be realized? Because the earth has a Counter Force that has authority over the entire earth, it can freely manipulate anything so that "something" that has the potential to destroy the earth but that unable to realize it. For example, like Gaia who amps Enkidu's Enuma Elish with the aim of canceling Gilgamesh's Enuma Elish so that the earth is not destroyed, Manaka uses Reality Warping via Root to manipulate reality but the effect of Reality Warping is canceled by Gaia and reality returns to normal as before, Zeus with his World Discipline Keraunos which can destroy the earth but was interfered by Ares, all of these was planned by Counter Force. There is one way that the earth can be completely destroyed, how? We have to go outside the time axis in order to avoid interference of Counter Force, this method was applied by Lion King, Goetia and Moriarty. Thus they can completely destroy the earth without interfered by Counter Force, it was explained in the Shinjuku, section 11.
Nasu created the terms of Anti-World and Anti-Planet is not without reason, it for dictate and proclaim that it is intended to destroy the world, planet and its parts, they CAN destroy BUT is interfered by Counter Force, the same as Avalon which is backed up by Counter Force because Avalon / inner sea is a place where the soul of the earth resides, Gaia with authority will keep it from being affected by interference from the dangers that threaten to destroy the earth. So destroying the earth including Avalon is possible as far as the statement goes, but it is prevented by the safety provisions that exist on earth, which is the Counter Force, therefore those who are able to destroy the earth always fail to realize it because the Counter Force brings some X which is equivalent to "something" that can destroy the earth so that the destruction of the earth does not actually happen. all statements about things that could destroy the earth are not hyperbole, they are capable but thwarted, they failed because it was caused by the authority of the Counter Force, simple.
Sorry for bad grammar.