@ddeimeke I agree to some extend, but I think some of your arguments are to negative.
GPG: yes, the web-of-trust is complicated. But I would argue that many people can just ignore it. For them it is simply "secure enough" to just encrypt the mail. How many people verify Signal fingerprints for Example? Almost nobody. And this is fine.
IRC: there are Web services and clients (for desktop and mobile) which make IRC really easy and nice to work with. I never used Slack, but I talks to people who use it and saw some video tutorial. For me it is still not more than a nice user interface for stuff you can also do with IRC.
At Nextcloud for example we decided to stick to IRC, Discourse and XMPP (internally) by purpose and I'm happy and proud that we took this decision.