They just ran away with the money they raised. These scam project members reamain active till the last date of ICO and suddenly disappear. Most of them deleting their social media accounts and leaving any discussion they are involved in. They no more care about reputation or getting flagged. They have achieved what they want and would repeat the same with some new IDs, website and a modified whitepaper.
Looks like the OP is not saying about fraudulent ICOs. The projects mentioned are still alive and in development, but their teams are mostly active on Telegram not on Bitcointalk. The OP is wondering why they publish news on the messenger channel and do not update their ANN thread here.
Do you think this is good for a project in general, let's admit it, Bitcointalk topics always shows up in search engine like Google while on telegram you have to scroll a lot or wait for an answer and they are missing up some potential investors who first look on Bitcointalk for project that they want to invest in..
Undoubtedly, Bitcointalk is the world's most popular forum regarded to Bitcoin and other crypto currencies. This is a convenient platform for discussing any questions about trading, investing, gambling, etc. But the Bitcointalk forum is not a chat.
You correctly noticed that Bitcointalk is followed by robots and indexed by Google and other search engines, so people can easily find the project they interested in and come here simply by clicking on the link.
Many potential investors read the Bitcointalk forum every day, so the teams that run ICO/IEO/STO campaigns are very active in their Bitcointalk announcement thread in order to attract investments and reach a soft cap and hard cap. Each thread is buried fairly quickly, so the team and the bounty manager post announcements very often. After that, they develop their product and communicate with the project community mostly chatting via messengers like Telegram.
In my opinion, not updating their Bitcointalk thread after a successful ICO is not very good for the project in general. Teams
should update their ANN thread at least every 3 months. In this case, the forum community will be informed that the project is alive, promising and worthy of additional investments.