After a recent experience with flat structures, i tend to be really suspicious. My experience was a total mess of organization, with slack bipping all the time, and nobody "in charge" of maintaining common sense in the architecture, with a long term vision.
Total chaos.
I think flat structures aren't always bad - if the organization is geared towards maintenance and care work, it's essential to be as flat as possible. Another good example would be research labs, where experimentation cannot happen in hierarchical envrionments.
For an organization that has definite goals and have to ship a product by a deadline, a flat structure can surely be detrimental to any progress. In an environment of competition (from outsiders) and scarcity, a flat structure will only create either chaos or an implicit form of hierarchy that is even more cruel than what should have been.
>Organizations which design systems (in the broad sense used here) are constrained to produce designs which are copies of the communication structures of these organizations.
Yeah there's a famous essay "The tyranny of structurelessness" or something like that. The TL;DR is that there is always a power hierarchy. If there isn't a formal one that just means there's an informal one which is usually much worse.
My experience with flat structure is the most stubborn opinionated people end up making all the decisions because they dont budge and get to escape all responsibility for bad calls. Better to have a designated lead.