I hate what it has done to Slack.

Specifically how it has bogged down a perfectly good piece of software in more notifications and redundant features.

One example is the Catch Up-feature, which is throwing notification badges even for channels from whitch I've explicitly silenced notifications.

Another example is the kanban board. Tried to make use of it, but got distracted by red badges every time I opened Slack with the intention of adding or tracking tasks.