It's no other reason than people who have access to the account only write updates for WRs they care about, unfortunately. But I agree - either we update all new WRs on social media, or we don't update any of them. In fact, the latter conclusion was what I personally came to after it became a bit too overwhelming to keep updating all WRs by myself (instead I mainly focused on the community update and making sure they're all mentioned there).
Though definitely not against giving access to the account to people willing to keep (all) the WRs up-to-date whenever they're set.