I hear the same about Monsey. And most landlords won’t even rent to you there if you don’t have schools for your kids set up yet.
What many posters here don’t realize, is that some families really HAVE TO move for various reasons. The reasons can range from literally no place for their kids to sleep due to their growing family size, to having boys and girls share a room past Bar/Bas Mitzva age, to the house no longer safe to live in as the roof or something major is in a state of disrepair, to the Landlord needing their apartment for a close family member and wanting them out.
The options to move within Brooklyn are very often cost-prohibitive. Waiting it out can be impossible, especially when the time to move for those with relatively older kids is only during the summertime as not to disrupt their school year.
There are no easy answers.