So what? Selling to such organizations tells more about the salesmen skills than actual merits of a product. For example, a lot of bigger and even more important organizations use Slack or Microsoft Teams, because a product they are sold works and does what they need.

On-premise software is nothing new. But the fact that some software can run on-premise and can interoperate between instances does not mean that it is a protocol. Mattermost can do that, is it a federated protocol too?