I’ve had limited experience with slack, but the whole way conversations map to workspaces at least got to be confusing to me, and I would have liked an experience based on me as a user, rather than having my user span workspaces and have to juggle them to figure out how to talk to whoever I’m supposed to talk to at the time.
Just two months ago, a security team member dinged one of our services for using Lets Encrypt, as “it’s not as secure as a traditional CA”.