Mostly useful for riding downhill. The point is to drop your center of gravity to help prevent going over the bars. If the downhills on your trail aren't that burly then a dropper post might not be much of an advantage.
I just got a bike last fall that came with a dropper post. The trails I ride in the Midwest aren't too burly so I only use it about 10% of the time.
On my previous bike...which didn't have a dropper post...I was doing some downhill jumps and landed kinda funny after one of the jumps and ended up cracking my carbon seat post. Dropper post might have been handy then.
https://www.montaguebikes.com/foldin...sts-explained/
https://www.bikeexchange.com/blog/bu...pper-seatposts
https://www.pnwcomponents.com/blogs/...a-dropper-post
https://www.redbull.com/za-en/five-r...a-dropper-post