Wow, that is kind of evil. I could understand if Slack kept, say, the last 20k or 50k and only showed the most recent 10k. For them to store all the messages indefinitely for all free servers means that they are incurring the same storage costs whether the server is free or paid. Are the bandwidth costs really that high to justify hiding all those messages (likely on the order of 100k or 1M for many servers) ?