The Minecraft developer no longer feels Reddit is an "appropriate place" to post official content to.
Minecraft developer Mojang says they are leaving Reddit.

At over 7.3 million subscribers, r/Minecraft is among the largest game-specific communities on Reddit. Minecraft developer Mojang, like many other game developers, often used Reddit as a means of sharing new information with their community. All of that is now coming to an end, according to statements shared by Mojang.

Mojang's Java technical lead for Minecraft, Mikael Hedberg, took to Reddit under the username sliced_lime to say that Mojang will no longer post official content to Reddit. This decision was made due to the rule and moderation changes that have hit many subreddits as a result of poor decisions from Reddit management.

As you have no doubt heard by now, Reddit management introduced changes recently that have led to rule and moderation changes across many subreddits. Because of these changes, we no longer feel that Reddit is an appropriate place to post official content or refer our players to.

We want to thank you for all the feedback and discussion you've participated in in past changelog threads. You are of course welcome to post unofficial update threads going forward, and if you want to reach the team with feedback about the game, please visit our feedback site at feedback.minecraft.net or contact us on one of our official social media channels.
These "changes" alluded to in the post more than likely have to do with how Reddit management has responded (or not responded) to protests against changes to Reddit's API that will kill most all third-party apps. Several communities have launched various campaigns against Reddit's ​decision to charge baffling high prices for API access, a decision that will lead to most all third-party apps shutting down. This is especially terrible for those that require accessibility features offered by third-party apps that the official Reddit mobile app completely lacks.

Many subreddits went "dark" by either turning private, turning into invite-only communities, or marking themselves as NSFW subreddits. Subreddits that are marked as NSFW means that they will no longer appear on the main Reddit feed for guests and Reddit cannot advertise on them. Reddit's response to a lot of this was to threaten and pressure mods to returning to normal operations. In some cases, Reddit admins outright removed mods and tried to replace them with new mods that will do the bidding of the admins.

Mojang tended to interact with the Minecraft Reddit community in several ways. One thing Mojang devs did on Reddit was post full changelogs for new Minecraft updates and then pull in feedback directly from responses. Mojang, at least sliced_lime, also often posted short videos highlighting the changes made to Minecraft in every snapshot release.

Whether or not other development or publishing studios will part ways from Reddit remains to be seen.