Recently, the open-source multi-instant messaging (IM) program Pidgin was updated to version 2.12.0. That's the good news. It's a very useful program if you work with people using multiple IM services. The bad news is that its developers couldn't add support to newer IM platforms, such as WhatsApp, Facebook Messenger, and Slack. Additionally, it will no longer support the deprecated Facebook XMPP, MSN, MySpace, Mxit, and Yahoo.
Why? In the former cases, it's because the people behind them have made it impossible for third-party programs to interoperate with them, or even to use federated identity so you can log in to them with an independent program. In the latter cases, several of them really are outdated, but with Facebook XMPP and MSN, it's because the vendors don't want you using their successor services unless you're using their application or front-end.
It was bad a few years ago when my colleague and buddy Jason Perlow wrote, "The number of instant messaging accounts that I have to deal with on a daily basis is absolutely mind numbing". It's only gotten worse since then.
So, as Joe Sneddon wrote at OMG Ubuntu, "The days of standards compliant chat protocols is gone. The age of federated messaging services seems to be over, with WhatsApp, Viber, Telegram, Wire, Allo, Skype, Facebook Messenger, WeChat, and countless others opting to 'own' the entire experience."
Why does this matter? Because while maybe everyone in your office uses, say, Skype or WhatsApp, your customers and partners may not. The IM vendors are interested only in keeping you within their closed island of communications. That's great for them, but it's lousy for you.
With public IM, you're outsourcing your IM to a third party. Think about it. With all too many services, your company has no contract, no service guarantees, and no real control over what these services may or may not do with your business IMs.
At the very least, if an IM vendor offers a supported service, as Slack does with Slack for Teams and Slack Enterprise Grid, buy it. Yes, you can use most of the services for free and you'll get exactly what you paid for.
In its earliest days, IM programs such as Internet Relay Chat (IRC) were meant to make it easy for us to work with each other in real time no matter who we worked for or where we worked. With the rise of incompatible IM services, we're actually moving backwards on the internet's interoperability promise.