No one is ever going to pay per-seat for tens of thousands of teenage volunteers. If you're an unusual customer (nonprofit, with lots of volunteers and program people in the slack) you might end up with a long term special deal recognizing those circumstances (charging you for employees but not others).
The biggest issue is the abrupt change in policy. Slack had wanted Hack Club's patronage and had supported it. (Shoot, getting Slack visible to tens of thousands of future decision makers instead of Discord where these users all naturally congregate was a major win!)
To abruptly demand a massive immediate payment after a month's worth of mixed signals, from a small nonprofit, is messed up.
The biggest issue is the abrupt change in policy. Slack had wanted Hack Club's patronage and had supported it. (Shoot, getting Slack visible to tens of thousands of future decision makers instead of Discord where these users all naturally congregate was a major win!)
To abruptly demand a massive immediate payment after a month's worth of mixed signals, from a small nonprofit, is messed up.