This is what people said about Twitter as well ;)
And slack, for instance, discontinued their IRC gateways as that limited their possibilities to "innovate" and I can image Slack, being pushed by shareholders, restricting free add-ons to getting data into slack (from Version control, business tools, task trackers, ...) but restricting getting data out to more expensive tiers (making transition of Slack harder)
But there are the key difference between open and proprietary protocols: Open protocols are slow to evolve (see also the state of mail protocols ... where innovation happens mostly in Gmail's protocols, not SMTP/imap/...) but allow wide variety of clients, while proprietary systems can evolve faster, but are more limited in clients.