Notice the binary size of the app is only 64KiB. In the demoscene this would be a disqualification as it's 676 bytes over the limit, but in this case I'll overlook it because of the sheer awesomeness of what you've done (and I'm sure trimming off 676 bytes wouldn't be too difficult ;-) More seriously, this is an excellent proof-of-concept that a Slack client does not need to use hundreds of MB of RAM and consume most…
I can't help but agree with you. Honestly I think it went to hell when we decided that it was acceptable to call an electron app native, but that may have been a symptom, not a cause.
At least with Electron you’re essentially forced to style everything - and ever since Windows 8 (or Windows Vista) Microsoft has been actively uglifying native widgets.