There's nothing wrong with social chat on Slack. It just needs to be either in a thread or, better yet, in a dedicated social channel.
Saying people shouldn't have social chat on Slack is like people shouldn't have social chat in the office kitchen because it's part of the same office complex.
Saying people shouldn't have social chat on Slack is like people shouldn't have social chat in the office kitchen because it's part of the same office complex.