It's coming soon-ish. Our first goal is to add position select (which you'll see really soon) and then build bans on top of that.
Bans have a few things that are pretty tricky to solve: As mentioned in the thread, the health of bans is tightly coupled to the number of champions in the game. It really has two pretty distinct manifestations, the first being an unsatisfying game if you ban an entire position out and then artificially moving access to ranked further down the line for new players. We'd really like to avoid both.
There's a compromise we may end up going with, which is serving you partial bans (3) while we wait for the full system. But even for that, there's still a minimum champ pool we need to hit.