Similar to you. There were several hints that the author didn't really understand software. The problem with waterfall wasn't that you had to do tasks in order, it was that you needed to know mostly everything in advance to get rid of issues at design time so they didn't bite you during coding.

Also, the rumblings of agile don't really point to anything to do with agile fundamentally, just the fact that people don't quite understand it or that management doesn't wholeheartedly embrace the mess.

"Agile meant that the team didn't really know what they were producing" - that is a Product Owner issue 100%.

So yeah, nothing's perfect but it's probably the least worse of the options we have!