I'm not too sure about the March of '21 events being hyped as potential super outbreaks because I didn't follow weather very closely back then. So admittedly, I don't know about those two events.
Outside of those two, though, none of the events listed there outside of 4/27/11 were genuinely expected to be super outbreaks (and 4/27/11 was only expected to be a super outbreak on the day-of based on how that day was beginning to pan out), and IMO only two were considered to have
potential to hit the ceiling of a super outbreak, which were 3/15/25 and 5/20/19. Every other outbreak was definitely not seen as a potential super outbreak contender. The only times I consider that to be so is when you have veteran meteorologists calling for comparisons to other extremely high end events in forecasts, like how James Spann began ringing alarm bells pretty far out in advance of 3/15 this year. You simply don't see that very often.
Days like 4/27/11 still potentially could have had flies in the ointment that only would have become apparent on the day of. When the satellite presentation of an extreme event became clear in the morning hours of that day, meteorologists
really began going hard on the alarms. A great example of this is on the
100 API radio show with Jim Stefkovich.
However, days like 5/20/19 and 3/15/25 were talked about as being
potential super outbreaks, but as those events began to unfold, it became very clear that they were not going to hit the ceiling. I don't know if 5/20 was being talked about as a super outbreak up until it lined out, but I do know for a fact that when we woke up and saw the messy satellite presentation on 3/15 we knew it wasn't going to hit the ceiling. Not that it didn't verify as a high risk, it just wasn't what it could have been.