My guess/experience - because there are probably layers of management and executives who have an uptime # in their OKRs or whatever is fashionable these days.

The decision to post anything about outages comes from the executive chain in many orgs lest they miss out on bonus compensation for the year.

This is the same reason services like docker and aws will very rarely call an outage an 'outage' - it's always 'service degradation', even when dockerhub is completely useless as it is right now.