It's not that useful in my part of world. Also, I'm not only interested in pop/rock bands. I also want jazz, classical, movie festivals, etc. That's why I follow handful of small venues, organizers and cultural magazines. It's all very niche and hard to follow otherwise.

For instance there's no way I would find about "Days of Organ music" few months ago. I didn't even know that there's a catholic cathedral with pipe organ in Belgrade, most churches here are orthodox and they don't have pipe organs.

This is just an example. There are other kinds of local interests you can only follow effectively on FB - hiking groups, sales in local music stores, environmental protests, whatever rocks your boat.

Fair enough, for me it's fairly useful even with niche genres, but promoters around here tend to use it too (or the info gets scraped because the area has more things going on). I've had free open air (no venue) concerts of Balkan folk pop in there!