Yeah, these are really poor examples of growth hacking. growth hacking is what Nikita bere does his TBH and gas app. What this blog talks about is simply things which are trying to portray themselves as great systems thinking and growth hacks, but are actually just incredibly basic things and not not hacks of any kind.
Wait, Slack was created in the same way Flickr was by Butterfield? I know this was true for Flickr but didn't realize it was for Slack as well.