Teams isn't going to directly take market share from Slack, but it forms a hard barrier limiting Slack's future growth. Large established organizations are switching to Teams, and finding it good enough that they'll never want to pay for Slack.
Those sound more like great features than "workplace bureaucracy".
To everybody who isn't a software developer and will likely never need Jira integrations and Slackbots, Slack is just another chat app.
For a paid software, Slack needs to win those people over too.