"Some" people, arguably. Nothing beats email for an easily-referenceable, structured and local/distributed system of record. Slack requires an always-on connection. Catching up on conversations after a lengthy break is far, far easier using email.
Slack is also disruptive in a way that email isn't. Slack demands attention, which breaks concentration on other tasks. Email can be dealt with at the recipient's leisure.
Slack is also disruptive in a way that email isn't. Slack demands attention, which breaks concentration on other tasks. Email can be dealt with at the recipient's leisure.