To surrender you must meet a number of criteria.
Relocation of the main castle was once meant as a last resort. But because of the surrender possibility, I think it is now only used for tactical reasons.
In the past, the so-called jumpers often turned out to be multi-accounts or players who were hardly present in the game and who wanted to get out with a big bang. Is it possible to bind the jumping of the main castle to some criteria? I myself think of a minimum average of hours that you must have spend on the game, before you can jump. So Jumping will be again a tactical act that you have to think carefully about instead of a way to get rid of surplus kingdoms.