" In the book, in a quite short period (of hundreds of years) three star system being completely destroyed. And they are destroyed in a way that will be easily noticeable through a simple telescope."

There are much more advanced civilizations, which collapse whole dimensions to win each other, so "dark forest" is still true for little ones. It's more like cockroaches should be quiet.

As for lucky coincidences, real life may contain even more of them, so I do not see how the sci-fi book can be bad because of that :-)

Wallfacer concept is an interesting one, BTW.