What would make the most important point of that slide stand out any more in a "real document" than in a slideshow? If anything, I would expect it to be buried even more - a slide and limited-time presentation forces you to be concise, while in a document there tend to be few limits on length.

I would say the disaster occurred despite PowerPoint, not because of it. It's not clear to me at all why the slide author thought all that text was needed, when it seems to communicate almost nothing. If anything I would blame it on the culture around "real documents", where having more information is treated as better (probably because they serve multiple functions - to educate, but also as a record of activities), even if it makes it bloated and hard to read.