To folder or not to folder ... that is the question

I think it is again important in which context you are. Metadata are still fine for structured data and "process-driven" stuff, like documents with defined and managed lifecycle. We as consultants were maybe a bit "over-enthusiastic" in the last ten years and pushed the message of using metadata too hard.

Microsoft tends to go the more agile way of collaboration and information sharing. Less managed processes, more local decisions, which information enters the system and who the coworking users are. Well-defined sets of metadata make these approaches more clumsy and irritating for end users. So for all new fancy stuff folders are back. But when you tend to implement your clients business cases with boring managed solutions they are as strong as ever.