Just an addendum to this post….
notpashut- As much as I respect the various Rabbonim- R’Avigdor Miller zz’l was never a Posek and neither was R’Shmuel Berenbaum zz’l. I do not know about the eiruv of Flatbush but there is an eiruv in Boro Park and it was organized by many outstanding poskim.
The fact is that there are people who believe in the eiruv and some do not. Every person should act according to his Rov and conscience. Each side has good reasons for theri Psak and let the Kehal follow those they want to follow.
There is no machlokes in Queens because even the ones who may not hold of an eiru allow the other side to practice theri way of halacha- as has been the case for man ycentuires until a Psak is ultimately accepted by the whole Klal.