This is a good observation. As a matter of fact, i have not seen any ICO lunched without passing through bitcointalk forum. Virtually every developer knows that this forum houses so millions of investors. Even developers who are yet to be registered here, still find their ways here or connect with someone who is already registered here in order to publicize their projects.
Yes, that. I have monitored ICOs that chose to bypass Bitcoin talk and then didn't do that well may not have been the only reason, but one of the glaring ones for sure.
Engaging with potential investors directly is vital, and the forum is one of the best places to do that, if not the best.
If it goes, something else will take its place, guaranteed.