Where's the social engineering part? Trying to convince people you aren't a scumbag so they become your friend long enough for you to swipe their password?
Actually, they don't use Slack because Slack would be the most expensive piece of software they license. The enterprise model from Slack is so prohibitively expensive it's like they're intentionally trying to drive away large customers.
I had an extension a while ago that I was attempting to publish to the Firefox app store and it was rejected on grounds of using eval. I don't remember why I needed to use eval, but basically this is something they do already. I'm guessing that previously they were allowing for an Angular exception.
These things aren't pain points in the browser the way they are in Node. I have never felt the need for an ORM in the browser. I have never dealt with client-side code that was using so many libraries I had to worry about whether exceptions would be handled via exceptions, or the first argument of the callback, or rejected promises. No one (at least, no one I know) is installing node modules like isArray to use in the browser.
Yes, these things _could_ technically apply to the browser, but it's not commonplace. In the node world, these are all things you deal with consistently.