Seriously though, I think this is exactly what is needed for IRC: a facelift. IRC is hugely superior to centralised tools like Slack for obvious reasons. But if people are moving to Slack it's not enough to say they should not do that, but try to actually offer a competitive user experience.
People tend to dismiss web application development for being careless, but at the same time forget that this is what made these clear text fairly rudimentary protocols popular. Until we get encryption built-in, more robust programming languages and figure out distribution on the desktop it's unlikely that the ecosystem will come back.
Even though open source is "cool" now, I can't help but feel it's mostly people working for companies that just want to export their technical debt for free and use open source as a marketing tool.
I think it's more that originally FOSS developers/users were hard-core's who were into the tech and the ideology of 'Free Software'. The user-base now has many people who are into 'open source' for the collaborative (group motivation) and perceived technical benefits at an infrastructure level. It's a benefit because there's more 'free' code flowing around, but the downside is that as soon as a proprietary thing is better the user-base moves to it - they have no link with ideology, they're linked to utility.
Also, I have to get invited, check my email, sign up, and skip the tutorial every time?
Also, in this particular case, Matrix also appears to be a well thought out platform for decentralised communication, one that is likely to be flexible enough to meet the needs of multiple different forms of communication.