The way I visualize it, the experts would primarily: a) Follow the hashtag so they could scroll it and answer questions b) Add it to their bio so their followers know where to go to get their questions answered directly from them No reason for them not to use the hashtag themselves though. Sticking with my doctors example, I'm sure docs would also occasionally have questions to throw at the other doctors in the community, regarding weird patient cases they're stumped on, or stuff like that!