Fortunately there's https://github.com/slack-ruby/slack-ruby-client, but it's not official. Although it seems to be a good example of a community driven library coming together. I haven't used it personally (I never interfaced with Slack in a Ruby app) but at a glance it looks like it has really good docs, a decent amount of contributors, well maintained, etc.. If I were building some Rails app that used Slack I'd likely reach for this and not feel bad about it.

Kind of a bummer on the other 2 tho. Thankfully I wouldn't be building too many apps using those tools, but I get the point you're making. In the grand scheme of things I think this also shows how much more popular Python is than Ruby.