Seriously, I don't know any top quality journals is using large quantity of postdocs as reviewers. In academy if one is invited by a top journal as a reviewer, that is an honor, meaning one is acknowledged by peers. In my field I can't think of any quality journals' reviewers are majorly post docs.

Also your pointing fingers at foreigners is quite disturbing. Why you think they caused the problem? Do you have any evidence? I don't think in any academic workplace you can say this without unfavorable consequence.