[my5thaccount]

The fact that they are ignoring this is a very bad sign. It's way easier to do and hasn't been done well and instead they are doing something really hard that people can already do easily outside the system. They've shifted their focus from their customers needs to beating the competition and it will their downfall.

[rl3]

Threaded discussion support is a major feature their competition touts, so arguably by adding it Slack would be crushing their competitors and serving their customers at the same time.