It's merely courteous to do so, not a requirement. Announcing hunts isn't a requirement either. And S ranks have been soloable since ARR. If I went through the trouble to find or spawn a hunt and could solo it, I did. It was especially bad during hunt release when B ranks didn't respawn every minute.

Making hunts tougher as things move forward, which they did, merely means you would need a sizeable party. Skilled players could get away with a Light Party if they didn't mind the time to whittle things down.

Yeah, it can be frustrating if you rely on others to find or spawn hunts just to arrive and itd already dead just as its equally frustrating to spawn one yourself, be courteous and announce it so others have a shot to get rewards for your effort, only to wait 6 minutes for several servers of people, pull at the announced time and have several dozen people complaining about "early pulls".