You are correct that there is history, but my point is that I don't believe the existence of long lived chat history (storing all messages longer than 3-6 month

You are correct that there is history, but my point is that I don't believe the existence of long lived chat history (storing all messages longer than 3-6 months) will be a blocker for a company to switch to a better chat platform. Chat should not be looked at as a durable store of critical, long term information. Slack is trying to create a vendor lock-in that doesn't exist.