If you don’t see a single tag from DT, it doesn’t mean that people don’t see what’s happening with these accounts. In addition, there is no rule to flag accounts for forwarding merits, at least without concrete evidence of their alternatives. Don't just think about participating in signature companies, perhaps some people do not understand the value of merit, and transferring it in such quantity was not something important for the sender.
At least as long as these accounts are not active, there is no need to tag them or worry at all.