Once you use it with a decent amount of people for work, things just get ‘lost’, because the frequency of messages in a channel is so high, info is missed, or employees working on different shifts need to spend a decent amount of time at the beginning of their day to review all the missed messages, some are relevant, most are not.
As you mentioned, there is also an inclination to send alerts or tasks to a channel, and similarly, the alert gets buried w additional messages, or you want up creating a bunch of ‘alert’ channels that you mute, or become hijacked and people start convos in those channels.
Also, the threading sucks. It is very difficult to get users to use threads.