What could be the reason for this ?
If that's actually really the case, I'm guessing that some projects simply just has too much publicity right off the bat on social media that the publicity for posting on Bitcointalk might be quite irrelevant. Especially when a certain project isn't planning on having a bounty campaign, they might not get that much traction here at all.
I am sure so. they already have a lot of publicity on social media and that makes them believe in the strength of their community.
Besides, at ANN, many of them did not respond quickly to other members' questions. It is rare for a team member or project developer to be active in the forum. even though it only represents an admin. but many are inactive. and social media I think is a very good way to build a strong market community.