I think in this instance, it is really both. The traffic calming aspect is using the marked bump-outs to narrow the lanes and reduce the amount of extra pavement available to drivers. This makes people slow down because it feels less safe to speed. It also helps prevent cutting corners and gives pedestrians some extra space for safety.

But all of these bumpout markings also provide opportunities to more clearly mark the lanes, turns, stops, etc. which is especially helpful at a convoluted intersection like this one.

As an aside - I think the biggest downside to these is that once one big truck has run over a flex post, many other people will feel comfortable driving over it too. So the DOT needs to either make an effort to regularly replace flattened flex posts, or put in something more solid like the planters in this photo.