I realize native apps on the three big platforms is difficult, but they're not using any native components what-so-ever. It's their web interface in a window. They could have used existing toolkits like QT, Gtk or something else, themed them to look like the Slack we're familiar with, and ditched the electron bloat.
I've tried to write a couple of prototypes in electron and have worked on some electron projects and I just don't see why people are flocking to it. Every tutorial is based around huge amounts of boilerplate or scaffolding, and unit testing always seems to require weird freaky hacks with modules.
I mean I guess if it works for them, good on them, but I'm still not going to take this as a sign to recommend or try new projects in Electron.