We don't use slack, but a similar tool called glip. As upper management I advised everyone turn off notifications for all except personal call outs. This means you can go back and collaborate as you need to, unless someone really needs to talk (remote team members, usually). If there is even increased urgency, they'll go talk or call. Most keep a tab open anyway to monitor conversations in their department rooms.

The gifs aren't a problem as we've simply asked the team to be appropriate with them. Maybe in individual chats they'll send them, but inspiring a greater goal means people have other things to focus on. Friday/birthday/work anniversary/strange occurrences... No problem. You also can't create an environment with no life to it if you want retention.

The biggest problem (once per year or so) has been gossip in private rooms that someone ends up reading. We have compliance exports that are available to understand what happened, but it's still not a fun situation. Undoubtedly these things would occur without the platform as well, but I'm hoping to either instill more respect for coworkers (if that's possible, some people just have bigger problems that need a psychologist to resolve) or take appropriate action to at least prevent it occurring with work tools.