about idref and prototype in Spring?

in section of "3.3.3.1.1. The idref element" of Spring document,it is
said that "If the 'client' bean is a prototype bean, this typo (and
the resulting exception) may only be discovered long after the
container is actually deployed".i wonder that why the prototype bean
would make difference?

what special thing does the prototype bean have for this scenario?

Help,plz
.