i really do not grasp the reasoning behind all of it...
ok, wp-cron is not reliable, because it works only when triggered by site traffic. ok, you'd better disable it and set a cron job.
little problem: i'm on shared hosting, i'm only allowed 1 cron job (spent on getting wp-con working... what if i needed it for something else? tough s..t!) and i can only set to 30min at the minimum (so no chance of triggers every 5-10 mins).
"get a better hosting": i hear you, and i might, but what if someone else cannot? tough s..t to that too? doesn't sound that great a reply to me...
what's really upsetting is to realise WP does know about it ON THE SPOT! meaning: i set the post to go live at, say, 7pm; i check on it at 7pm+10seconds, sure enough WP has already marked it with the error message... uh???
so WP knows it's programmed, knows it's just missed the deadline, but does nothing, apart from telling me it missed it... isn't that a bit of a joke?
i had to use "Missed Schedule WordPress Plugin Fix" (https://wordpress.org/plugins/missed-schedule-wordpress-plugin-fix/) - for some reason it does not come up in "search plugin" in WP admin (maybe because it hasn't been updated for too long? but then why is it still in the repo?), so i had to download it as a zip and upload in WP admin.
it does not publish my post at the programmed schedule, but within some 10 minutes from it. that's good enough for my current need, but sorry WP, you've turned me into a spoiled brat, i'm now used to "good, sound, robust" WP solutions, "good enough" is not... enough for me anymore.