Discord welcomes open-source communities and is quite popular in the React community. If you are adding an open-source tool to the React ecosystem, those are both good reasons to prefer Discord. I certainly wouldn't want to build an open-source community on Slack after the way they handled Reactiflux.
From a comment on reddit: Most developers who use OSX do not develop for OSX/iPhone, but instead deploy 100% of their code to Linux VMs on EC2 or Digital Ocean. Their toolchain is usually 100% OSS terminal-based tools such as Vim/Emacs, tmux, clang/gcc, PHP/Python/Ruby, zsh/bash; all of which are available via Linux package managers (and have better support on Linux). While homebrew is nice, it's package selection is much smaller than APT/DNF/Pacman, and it's source-based so have fun waiting for LLVM to compile...
Eventually I realized I was basically a Linux user and I was trying to make OS X work like Linux. According to stack overflow dev surveys they show Linux experiences a 10-fold increase in usage amongst developers compared to it's typical rate of usage on the desktop. This also drew me toward Linux. OSX only experiences a two-fold increase in usage amongst developers and Windows actually experiences a large decrease in users compared to their desktop monopoly. Right now I'm developing React native applications completely in vim.
If this application ever comes out for Linux I'll definitely install it and give it a try. Only being on OS X makes it inaccessible for most developers.
Deco is an Electron app, so it should build for Linux without too much trouble. None of us are Linux experts, so we'd be very happy to take any pull requests for Linux support if you have the expertise. As an indicator of demand, we have 2x the beta signups for Windows as Linux though, so we're currently prioritizing Windows support.
We plan on having a commercial license for companies that want to make closed-source modifications. We like the idea of charging companies much more than charging individual developers :)