In my opinion, what you want from statuspage depends on your product and how your customers are using it. Automation strikes me as plausible if your product is a well-defined set of APIs but it’s borderline impossible for a complex web app with many functions which each may or may not be critical. SLO alerts can work here but presuppose you have good SLIs. And capturing good SLIs for a complex product is a whole lot of work that small companies won’t prioritize. All of this is to say, there are downsides to automation that have nothing to do with the biz-side bullshit you’ve correctly noted.
Preventing alert flapping is hardly "very highly polished", it's the base level for having even internal monitoring. And if it works for you internally, you could definitely make some automatic information available.
It's not rocket science we're talking about. Having a status page that can automatically say "Everything OK" or "Something seems to be not OK" would even be enough, but most companies don't offer something like that.
Any medium to large sized company will, at any given time, have dozens or hundreds of alerts going off. How do you know which ones should equal an "outage" on status.myco.com?
edit I just checked, my company currently has 2079 monitors in an ALERT status. Some of those are probably real ongoing issues, maybe even some customer facing issues...but there does not appear to be any reason to update our status page.
For it to work, you have to know exactly which monitors could go into exactly which states (or range of values, etc) such that it constitutes a user facing outage that should be displayed publicly.
So you have to have automation around: How many users are affected? HOW are they affected? Is our homepage down but APIs still work? Is 1 API having issues but the other 100 just fine? Is there just some elevated latency but everything still works fine, or is it so elevated that we would call it an incident? Is it an internal tool that's broken? Is this a real alert or just an incidental alert due to a planned failover or a deploy and the metric loss is not indicative of user experience? Etc, etc.
It's truly an impossibly hard problem.