I can say that people in Israel prefer facebook groups for many reasons:

1. It allows for "team search". My friends knew I'm looking, so they tagged me in relevant posts they saw. Can't do it anywhere else (including marketplace by facebook themselves)

2. It allows for group communication with the publisher of the post. One asks - everybody sees.

3. It gives a sense of power to those who seek to rent. Many posts with high prices have comments like "You are crazy", "You are a pig", "whoever pays this much is as sucker". It almost warms the heart, we fight the greedy landlords. It almost make it fun, like a witch hunt.