I think that the main difference is that unix tools are intended to work which each other. Therefore needing less line of code. As opposed on other systems.
That was exactly part of the point I was trying to make with the article. The other, that I left unsaid but should probably add explicitly, is that Slack et al. run on a server with a kernel, but choose to ignore the access control capabilities of said kernel and instead chose to reimplement them. I think it is a shame, and more software should strive to be security agnostic instead of reimplementing access control for the umpteenth time.
