When I’ve been at companies large enough to need to solve communication issues, I’ve seen two major styles:
1) Need something? Post in the relevant channel. Use @s if appropriate. If you’re in the wrong place, someone will let you know. Break off to private chats when it makes sense, but mostly not. Folks have a good idea what‘s going on because most exchanges halfway-relevant to what they’re working on or connected to take place in public.
2) Need something? Ask around until you find the right person to talk to, then communicate with them. If electronic, DM or email them, don’t contact in a public channel (there may not even be one that makes sense for the chat). Communication is a network of who-knows-who-to-talk-to. Messaging app is mostly oriented around ad-hoc group and individual chats rather than channel-focused (thanks, fucking MS Teams, for practically enforcing this style at the tool level). If you’re not around to overhear things in person, you won’t know wtf is going on.
IMO the latter is clearly just dysfunctional, but this dysfunction is far less painful in-person—it seems to work basically ok, mostly, except that everything takes a little longer than it should. However, all its problems are brought in the open with WFH, and for someone who hadn’t seen the other (better, no matter where everyone’s working) style, I can see how they might think their struggles with WFH are because of WFH.