Just a few days ago Facebook decided to oblige iOS users to install Facebook Messenger to chat and thus start using Facebook ...
A revenge took place right after Facebook decision; users start low ranking both the Facebook and the Facebook Messenger Apps on the app store to express their anger and unsatisfaction.
|Facebook App rating|
Thanks to the jailbreak community and to a jailbreak tweak submitted on cydia called FBNoNeedMessenger ; you can bypass this restriction and go back to normal use of Facebook chat.
FBNoNeedMessenger is a free jailbreak tweak available on cydia on BigBoss repo.
Keep in mind the tweak has no options to configure, just install it and you are good to go.