I wonder how much of that comes down to culture. Since going remote I have come to wonder if a direct-message-first chat culture is harmful to collaboration.
The same people DMing however will also extol the virtues of posting in public and lament why there is not more conversation happening in the open.
It requires to be comfortable exposing lack of knowledge or saying weird things to peers, and be confident it will be taken in good faith. As you point out, that requires a whole level of culture building.
There's no question! It absolutely is.